Jump to content

Recommended Posts

Posted

Why doesn't Tarzan have a beard when he lives in the jungle without a razor?

Why do we press harder on a remote control when we know the batteries are flat?

Why do banks charge a fee on 'insufficient funds' when they know there is not enough?

Why do Kamikaze pilots wear helmets?

Why does someone believe you when you say there are four billion stars, but check when you say the paint is wet?

Whose idea was it to put an 'S' in the word 'lisp'?

What is the speed of darkness?

Why is it that people say they 'slept like a baby' when babies wake up every two hours?

If the temperature is zero outside today and it's going to be twice as cold tomorrow, how cold will it be?

Do married people live longer than single ones or does it only seem longer?

How is it that we put man on the moon before we figured out it would be a good idea to put wheels on luggage?

Why do people pay to go up tall buildings and then put money in binoculars to look at things on the ground?

Did you ever stop and wonder.......Who was the first person to look at a cow and say, 'I think I'll squeeze these pink dangly things here, and drink whatever comes out?'

Why do toasters always have a setting so high that could burn the toast to a horrible crisp which no decent human being would eat?

Why is there a light in the fridge and not in the freezer?

Why do people point to their wrist when asking for the time, but don't point to their bum when they ask where the bathroom is?

Why does your Gynaecologist leave the room when you get undressed if they are going to look up there anyway?

Why does Goofy stand erect while Pluto remains on all fours? They're both dogs !

If quizzes are quizzical, what are tests?

If corn oil is made from corn, and vegetable oil is made from vegetables, then what is baby oil made from?

If electricity comes from electrons, does morality come from morons?

Why do the Alphabet song and Twinkle, Twinkle Little Star have the same tune? Stop singing and read on......

Do illiterate people get the full effect of Alphabet Soup?

Did you ever notice that when you blow in a dog's face, he gets mad at you, but when you take him on a car ride, he sticks his head out of the window?

Posted

You ask too many questions......:rolleyes:

There are no answers.... only questions......

Could be worse, I reckon.

Everyone seems to have answers vacant of the questioning strategy.

Fear of curiosity and challenging.

Posted

You ask too many questions......:rolleyes:

There are no answers.... only questions......

Could be worse, I reckon.

Everyone seems to have answers vacant of the questioning strategy.

Fear of curiosity and challenging.

Things can always be worse. Much worse. That is the main thing that keeps me cheerful.

SC

Posted
Everyone seems to have answers vacant of the questioning strategy.

Good evening Professor.

That was a deep post. Please give me a few days to work out its inner meaning.

But I have to go out now ............. my fridge is currently vacant of beer.

By the way, do you remember that Sex Pistol's song called Pretty Vacant? For some bizarre reason, it reminds me of you.

Posted
Everyone seems to have answers vacant of the questioning strategy.

Good evening Professor.

That was a deep post. Please give me a few days to work out its inner meaning.

But I have to go out now ............. my fridge is currently vacant of beer.

By the way, do you remember that Sex Pistol's song called Pretty Vacant? For some bizarre reason, it reminds me of you.

To be fair, your opinion would have been just as valid without voicing it (pots and kettles!)

ZZaa is one of the few posters who helps maintain our own superiority complex

SC

Posted
Everyone seems to have answers vacant of the questioning strategy.

Good evening Professor.

That was a deep post. Please give me a few days to work out its inner meaning.

But I have to go out now ............. my fridge is currently vacant of beer.

By the way, do you remember that Sex Pistol's song called Pretty Vacant? For some bizarre reason, it reminds me of you.

To be fair, your opinion would have been just as valid without voicing it (pots and kettles!)

ZZaa is one of the few posters who helps maintain our own superiority complex

SC

Thanks for the defensive posturing, Cowboy.

Abnormal, I prefer to be. Makes me feel better about myself - considering what I absorb here.:jap:

Posted
Everyone seems to have answers vacant of the questioning strategy.

Good evening Professor.

That was a deep post. Please give me a few days to work out its inner meaning.

But I have to go out now ............. my fridge is currently vacant of beer.

By the way, do you remember that Sex Pistol's song called Pretty Vacant? For some bizarre reason, it reminds me of you.

To be fair, your opinion would have been just as valid without voicing it (pots and kettles!)

ZZaa is one of the few posters who helps maintain our own superiority complex

SC

Thanks for the defensive posturing, Cowboy.

Abnormal, I prefer to be. Makes me feel better about myself - considering what I absorb here.:jap:

Professor ........... might it not be possible that you're absorbing just a little too much .

Posted

Rolling Joe gave me the answer back in 86 in WintersGills bar on Great Western Road .

" You see son " sayeth Joe

" The answer is ... there is no answer ! "

"And now we're gonna play , whole lot of shackin goin on hahahahahahaaaaaggghhh"

Posted
Everyone seems to have answers vacant of the questioning strategy.

Good evening Professor.

That was a deep post. Please give me a few days to work out its inner meaning.

But I have to go out now ............. my fridge is currently vacant of beer.

By the way, do you remember that Sex Pistol's song called Pretty Vacant? For some bizarre reason, it reminds me of you.

I remember it , it goes

"there's no point in asking , you'll get no reply " and so on

Posted

Why doesn't Tarzan have a beard when he lives in the jungle without a razor?

He does, just shaves for movies and the television

Why do we press harder on a remote control when we know the batteries are flat?

That's why the batteries are flat

Why do banks charge a fee on 'insufficient funds' when they know there is not enough?

Because they can

Why do Kamikaze pilots wear helmets?

Makes them look Mahvelous!

Why does someone believe you when you say there are four billion stars, but check when you say the paint is wet?

To be sure, obviously they already don't trust you!

Whose idea was it to put an 'S' in the word 'lisp'?

Mine

What is the speed of darkness?

186,000 mps...same same as light

Why is it that people say they 'slept like a baby' when babies wake up every two hours?

They don't

If the temperature is zero outside today and it's going to be twice as cold tomorrow, how cold will it be? 00

Do married people live longer than single ones or does it only seem longer?

Sure seems like it

How is it that we put man on the moon before we figured out it would be a good idea to put wheels on luggage?

First things first

Why do people pay to go up tall buildings and then put money in binoculars to look at things on the ground?

They put money in binoculars?

Did you ever stop and wonder.......Who was the first person to look at a cow and say, 'I think I'll squeeze these pink dangly things here, and drink whatever comes out?'

Me

Why do toasters always have a setting so high that could burn the toast to a horrible crisp which no decent human being would eat?

I like it burnt, with peanut butter

Why is there a light in the fridge and not in the freezer?

How do you know there's not, it goes off when you open the door.

Why do people point to their wrist when asking for the time, but don't point to their bum when they ask where the bathroom is?

I do

Why does your Gynaecologist leave the room when you get undressed if they are going to look up there anyway?

I don't have a gynaechologist

Why does Goofy stand erect while Pluto remains on all fours? They're both dogs !

My dog can stand erect and on all fours. So??

If quizzes are quizzical, what are tests?

Testicles

If corn oil is made from corn, and vegetable oil is made from vegetables, then what is baby oil made from?

Babies

If electricity comes from electrons, does morality come from morons?

No

Why do the Alphabet song and Twinkle, Twinkle Little Star have the same tune? Stop singing and read on......

Next....

Do illiterate people get the full effect of Alphabet Soup?

No

Did you ever notice that when you blow in a dog's face, he gets mad at you, but when you take him on a car ride, he sticks his head out of the window?

Yes

Anything else I can do for you?

:unsure:

Posted

Thank you for all replies. some inane... some logical, but all well received. Now I will retire.

But I willl Leave you with this:

What is the square root of minus one?

Posted

Thank you for all replies. some inane... some logical, but all well received. Now I will retire.

But I willl Leave you with this:

What is the square root of minus one?

It can be i, j, or k.

http://en.wikipedia...._Rowan_Hamilton

Reference - Yahoo

It seems that some people are under the misapprehension that the square root of -1 does not exist...

As a pure number this is true, but there are many practical engineering needs where you need to use the square root of -1 to solve a very complex problem.

Generally the square root of -1 is given to be the small letter "i"

It can sometimes be given other letters such as "j" or "k". This is used to identify the square root of -1 in each of the three different dimensions (x axis, y axis and z axis), this is so when complex calculations are done, you can still identify each of the 3 directions..

As long as you remember that the algebraic use of "i" is as follows

i ^2 (squared) = -1

  • You cannot square root a negative number. This is because a square number is when two numbers that are exactly the same are time together to get a result, however you can't time the same numbers to get a negative number because:
    + x - = - (The numbers would not be equal)
    + x + = + (The numbers would be equal but would give you a positive instead of a negative)
    - x - = + (The numbers would be equal but would also give you a positive)
    Sorry dude, :)
  • btw you are lking not 4 the square but the square root no.1 answer and it is impossible ask an a-level maths teacher you can only square root positive numbers and square roots of positive numbers can be negative or posistive so the square root of 1 could be minus one

    but the square root of minus one does not exist

    Source(s):

    trust me on this i am the source of all knowledge

    keep to your secret promise...

    10 points now

    pretty plz

    [*] It's impossible to square root a negative number. Although, for that particular equation, it can be substituted with the variable i. [*]

    -1 x -1 = 1... so it's one.

    • 3 months ago

Posted

Obviously, both you and the Yahoo source are mistaken.

The square root of -1 is normally called i, and sometimes called j or k. (The earlier part of you reply, seems to accept this idea).

The square root of a negative number, is an imaginary number, but a number nonetheless.

The end of your reply uses rules for Real numbers, which are not the same as rules for Imaginary numbers ( as I understand the rules).

We kinda knew that -1 x -1 was = +1 at about 8 years of age. (all Real numbers, and absolutely nothing to do with i)

Posted

Jombom

is this any better?

mplex Numbers - an Introductiont.gifpixel_grey.gift.gift.gif

t.gifpixel_grey.gifpixel_black.gift.gifContact Us

Like this page?

Send it to a friend!

t.gift.gif

mathsclass_promo.jpg

Many of us find anything to do with numbers complex, not to say downright confusing. We fret our way through school learning more arithmetic, algebra and geometry than most intelligent people would need in a lifetime. That's not to mention the seemingly useless trigonometry and calculus.

This Entry introduces a branch of mathematics which is even more detached from the real world. In fact, the first thing to say about complex numbers is that they are not all real.

Really?

Other numbers are real. Mathematicians use the word 'real' to describe numbers which you can measure. Three, -56.3, the square root of 42, and pi (3.14159...) are real. Complex numbers have a part which is real and a part which is not - we call this part 'imaginary'.

To try to see an imaginary number, take your calculator and try to find the square root of -1. You were probably told at school that you 'can't have' a square root of a negative number. Your poor calculator will try its hardest to give you an answer, but it will fail, maybe spectacularly, and it will display an error message which the calculator designer programmed into it for this purpose. Maybe it will say 'E' or 'Error', or fill the display with asterisks or something. It makes you wonder whether, if the programmer hadn't told it what to say, the calculator would now be ushering you into a window on a new world of imaginary numbers.

This square root of minus 1 is the basic imaginary number. Mathematicians1 call it i. (It's funny how the moment mathematicians discover an interesting number they immediately give it a letter instead; at least this one's not Greek.)

So there it is: i.

i squared is -1.

Figment of your imagination?

As we said earlier, a complex number has a real part and an imaginary part. There are a number of ways to write them, and here's one. This is called Cartesian notation, after René Descartes, who was somewhat suspicious about this strange mathematics.

(4 - i) is a complex number. The real part is four, and the imaginary part is -i.

(-7 + 3i) is another - the real part is minus 7 and the imaginary part is 3 times i.

To visualise complex numbers, we need to plot them on a special graph. The x-axis (the one which goes horizontally across the graph) is used to plot the real part of the number, and the vertical y-axis is used to plot the imaginary part - the number by which we multiply i. These axes meet at the origin, a point where the values of both are zero. So, a number like (2 + 4i) will be a point on this graph which is two units to the right of the origin, and four units above it. (-7 -3i) will be a point 7 units to the left of the origin and 3 units below it. This graph has a special name, the Argand Diagram, after the 19th Century French amateur mathematician Jean-Robert Argand, who published the idea in 18062. If you've ever studied vectors, then you will find this graph familiar. Numbers on it can also be described using 'polar representation', which makes use of their distance from the origin (the 'size' or 'modulus' of the number) and the angle of the line joining the number to the origin, as measured anticlockwise from the real axis (this is known as the 'argument').

So, whose idea was this?

We can blame the Italians for this one. Renaissance mathematicians were studying equations which didn't seem to have any solutions, when they came up with a couple of new concepts. One was negative numbers, the other was imaginary numbers, but the latter didn't really become accepted until the 19th Century, following work by German mathematicians Georg Cantor and Julius Dedekind.

What can you do with them?

Well, you can do most things that you can do with real numbers (with some exceptions), and some odd things besides.

You can add and subtract them - just add or subtract the real and imaginary parts separately. The sum of the two numbers above is (-3 + 2i). The difference is (11 - 4i).

You can multiply them together, by multiplying each element in one number by each element in the other, as if you were multiplying algebraic expressions in brackets. Just remember that when you get an i squared, you can replace it with minus 1.

(4 - i) x (-7 + 3i) = -28 + 12i + 7i + 3 = (-25 + 19i)

Dividing them is a bit trickier. You need to multiply the numerator and the denominator by what is called the 'complex conjugate' of the denominator. The conjugate of a complex number is the same number, but with the sign of the imaginary part reversed. The complex conjugate of (4 - i) is (4 + i) and that of (-7 - 3i) is (-7 + 3i). Doing this multiplication removes the i's in the denominator. We'll leave this for you to try at home. Have a go at dividing (1 + i) by (1 - i), using this method3.

Why are they so interesting?

As the Italians found, they let you solve 'impossible' problems!

Here's one - you have 20 metres of fencing, and you want to enclose a rectangular area of 40 square metres. How long are the sides? (Go on - try it.)

Given up? Well, you can do it with complex numbers, and the answer is that the long sides are (5 + the square root of minus 15) metres and the short sides are (5 - the square root of minus 15) metres.

OK, it's an impossible answer - if you don't believe it, just ring up B&Q4 and try to order the square root of minus 15 metres of larch lap - but the point is, it's an answer that fits the question. If you multiply the sides you get 40 square metres, and if you add them all you get 20 metres.

That doesn't sound useful to me

Newton, practical as ever, saw these numbers purely as an indication that a problem couldn't be solved, but in fact they have particular use in pure (theoretical) mathematics. The German mathematician Carl Friedrich Gauss studied them in the early 19th Century, and complex numbers which have integers for both the real and imaginary parts are known as Gaussian integers. The Swiss mathematician Leonard Euler derived the well-known Euler Equation which links complex numbers to trigonometrical functions.

For a more practical example, we'll look at a problem studied by the Italian mathematician Rafael Bombelli in the 16th Century.

This is quite involved, and we won't go into detail, but Bombelli was looking at problems with simultaneous equations like, for example:

x
2
+ y = 21
and
xy = 20

These lead to the cubic equation5:

x
3
- 21x + 20 = 0

Now, Bombelli knew a formula for solving equations of this form, and it had to be derived in two stages. The first stage was to find a number g such that...

3x = 3g
1/3
- 7g
-1/3
(Note:
g
1/3
is another way of saying the cube root of
g
.)

...but the number he found using his formula for g was complex - it involved the square root of a negative number. He then discovered that another complex number when cubed gave the required value for g - for this example g1/3 turns out to be (2 + the square root of minus 3) - but the clever thing was this: when he completed his formula using this number, the answer it gave at the end was x = 4. So x turned out to be a real number6, but in order to calculate it, he needed to use complex numbers.

So there you have it. Complex numbers are useful to mathematicians as they extend our mathematics and enable us to solve real problems which were previously unattainable through our restrictions on real solutions throughout. Not only this, but complex numbers provide a way of describing two-dimensional spaces, leading to their use in electrical engineering, control theory and quantum mechanics.

<a class="pos" href="
6
The full solution to this example is x = 4 and y = 5.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.



×
×
  • Create New...