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PostPosted: Fri May 15, 2009 8:15 am 
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Find the value of a and b in the following question.

2 to the power of a x 5 to the power of b =200

I use prime factorization to work out 2x2x2x5x5, therefore the value of a =3 and the value of b=2

I wonder what level would you expect this sort of question in the exam? Thanks in advance.


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PostPosted: Fri May 15, 2009 10:35 am 
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I can't answer the question on level... we'll have to wait for a teacher to do that...

... but... it does seem pretty simple... i.e even if you don't factor it... there is an obvious 25x8 there. Factoring, given that 2 and 5 are prime, of course is the correct approach.

I'll try it out of the DCs later :twisted:

Regards
SVE

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Animis opibusque parati


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PostPosted: Fri May 15, 2009 3:35 pm 
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About a level 7 -ish


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PostPosted: Tue May 19, 2009 9:34 pm 
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Surely it is simpler than that. It cannot be 5 cubed because that will give 125, therefore it has to be 5 squared. The rest follows.

QED


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PostPosted: Tue May 19, 2009 9:47 pm 
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It's hard to judge because the full question hasn't been quoted - if it's all written in algebraic form it makes it harder.


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PostPosted: Tue May 19, 2009 10:07 pm 
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Location: Berkshire
and this one, pls...

1/x=3/4

What is the value of x?


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PostPosted: Tue May 19, 2009 10:10 pm 
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er bit late - back from work and out with the beer ....

1/x=3/4
multiply through by x -> 1=3x/4
multiply through by 4 -> 4=3x
divide through by 3 -> 4/3=x
x= 4/3 or 1.33333333333333333333333

:shock: - oops there's a simpler way I've just realised


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PostPosted: Tue May 19, 2009 10:19 pm 
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Thanks Herman, that's what I made it. But confusion is, are you allowed to make the denominator a mixed number???


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PostPosted: Tue May 19, 2009 10:20 pm 
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now I'm feeling bewildered!!! what's a mixed number?


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PostPosted: Tue May 19, 2009 10:23 pm 
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:lol:

sorry, I meant a whole number part and a decimal/fraction part like 1.33, by mixed number.

Normally you'd only have a whole number as a denominator. (well in the lower types of maths I've done, you do :wink: )


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