Ratio and Proportion

• Oct 17th 2009, 05:06 AM
Ratio and Proportion
Hello!
This is a question about ratio and proportion, which I've tried to solve, but got the wrong answer. The correct answer is apparently 2, but I got someting like 0.0042 - and I am not sure what I did wrong.
Therefore, I would appreciate your help :)

The question is:
a+b = 1/6

((a-b)^2 + ab) / ((3a^3) + (3b^3)) = ?

Thanks! :)
• Oct 17th 2009, 05:12 AM
Quote:

Hello!
This is a question about ratio and proportion, which I've tried to solve, but got the wrong answer. The correct answer is apparently 2, but I got someting like 0.0042 - and I am not sure what I did wrong.
Therefore, I would appreciate your help :)

The question is:
a+b = 1/6

((a-b)^2 + ab) / ((3a^3) + (3b^3)) = ?

Thanks! :)

HI

$\frac{(a-b)^2+ab}{3a^3+3b^3}$

$=\frac{a^2-2ab+b^2+ab}{3(a+b)(a^2-ab+b^2)}$

$=\frac{a^2+b^2-ab}{3(a+b)(a^2-ab+b^2)}$

cancel off

$\frac{1}{3(a+b)}$

You should be able to take it from here .