Help Needed

[Namphonny]

My son has just returned from taking the government maths exam for P6 students.

The first line of the first question was as follows:

a * b = a X [a + b] - 1 and it goes on the say if a * b = 35 find [a/b + b/a].

Can any kind mathematician give me a clue what this means? I guess what I am really asking is what does the asterisk mean? Google doesn't help.

I shall refrain from commenting on the suitability of this for an eleven year old primary school student.

[Boater]

the astrix means times by

[loong]

If the asterisk is meant to be a multiplication symbol, then what is the X ?

It doesn't make sense to me.

[Boater]

an astrix is normally used as a multiplication symbol ...

it makes sense here a * b = 35 find [a/b + b/a]. IE a x b = 35 find [a/b + b/a].

If the asterisk is meant to be a multiplication symbol, then what is the X ?

as the x is a capital , it may possibly refer to X number ... ie the hidden number.

[Boater]

but from what i see a = 5 and b = 7

[phetaroi]

In re suitability...in my school in the States, that is not atypical work for 7th graders, or in the advanced math program at least a year younger. That is not to say that this former principal could do the problem!

[loong]

but from what i see a = 5 and b = 7

Why?

As the X has nothing to relate to, the question is just sheer nonsense and impossible to answer Unless the X is another multiplication symbol, then a = 1 and b =35

[noise]

but from what i see a = 5 and b = 7

Why? As the X has nothing to relate to, the question is just sheer nonsense and impossible to answer Unless the X is another multiplication symbol, then a = 1 and b =35

I think Loong is correct. If X is tossed in as a variable like a and b, then there is insufficient info. If the instructor wasn't paying attention, it is very likely he/she inserted the X as a mulitplication indicator.

Of course, if students had really been taught this, they would know that a*b is the same as ab. So the simpliest way to write it would be: ab=a[a+b]-1 and ab = 35: find [a/b + b/a].

Written that way, it quickly works out to Loong's values for a and b.

[Namphonny]

but from what i see a = 5 and b = 7

Why? As the X has nothing to relate to, the question is just sheer nonsense and impossible to answer Unless the X is another multiplication symbol, then a = 1 and b =35

I think Loong is correct. If X is tossed in as a variable like a and b, then there is insufficient info. If the instructor wasn't paying attention, it is very likely he/she inserted the X as a mulitplication indicator.

Of course, if students had really been taught this, they would know that a*b is the same as ab. So the simpliest way to write it would be: ab=a[a+b]-1 and ab = 35: find [a/b + b/a].

Written that way, it quickly works out to Loong's values for a and b.

I am afraid that the significance of my question has been lost so far - perhaps I should have mentioned that I have a degree in maths.

The asterisk between the a and b is a symbol of some kind that I have not met before. I tried to put it in bold type but it does not show up very well. It clearly has some specific meaning and must be in use in Thai schools but I have not been able to find it. On the right hand side of the equation the X is a normal multiplication sign.

My immediate thoughts were (1) vector analysis (cross product etc) which is ludicrous at primary level, (2) programming - about which I know very little but there is such a symbol in C++, (3) set theory which seems the most likely but has no such symbol that I know of.

I would be very grateful if someone can explain the meaning of the symbol.

[loong]

http://en.wikipedia.org/wiki/Table_of_mathematical_symbols

second from the bottom - but goes way over my head

[Namphonny]

http://en.wikipedia.org/wiki/Table_of_mathematical_symbols

second from the bottom - but goes way over my head

Thanks, yes I saw that but remember this is a primary school exam paper. Surely it must be checked by at least one examiner who is not insane.

[noise]

I am afraid that the significance of my question has been lost so far - perhaps I should have mentioned that I have a degree in maths.

The asterisk between the a and b is a symbol of some kind that I have not met before.

I, too, have a degree in math and have seen the asterisk used for multiplication many times (regardless of what Wikipedia says the correct meaning is). It would not surprise me to see it used in 6th grade to emphasize multiplication is to take place.

I still think that unless the asterisk and the X mean multiplication the equation makes no sense (i.e., is unsolvable).

I asked a M5 honor student about the lilkelihood this was taught in P6 and she was very dubious, regardless of level of the students.

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[Namphonny]

I think that I have at last teased out the meaning of this question. It is not a normal equation and the asterisk is not a multiplication sign. I think that the idea has been taken from Java script where this symbol is used to mean the multiplication of two sets of values. On the left of the equals sign it is only possible to write 5 x 7 because these are the only factors of 35. Therefore 'a' can only be 5 and 'b' must therefore be 3.

This question was no 1 on a 40 question paper taken by many thousands of Thai primary school students last Saturday. I have been informed that many students were able to answer the question but I feel sure that the majority could not and what annoys me is that the experience would have destroyed the confidence of many. Some of the other questions are more difficult and beyond grade 10 standard in the UK.

I suppose that you could argue that the actual solution is quite simple but to me it demonstrates a perfect example of "knowledge without understanding".