Hello!

This is a question about ratio and proportion.

Attachment 13400

When I solve the question I get the answer to be sqrt21, which isn't correct. The correct answer is a).

I would appreciate your help :)

Thanks,

Amine.

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- Oct 17th 2009, 05:42 AMAminekhadirRatio and proportion 2
Hello!

This is a question about ratio and proportion.

Attachment 13400

When I solve the question I get the answer to be sqrt21, which isn't correct. The correct answer is a).

I would appreciate your help :)

Thanks,

Amine. - Oct 17th 2009, 05:57 AMmathaddict
HI

$\displaystyle a+b=\sqrt{(1-\sqrt{5})^2}+\sqrt{(\sqrt{5}-\sqrt{20})^2}$

$\displaystyle =|1-\sqrt{5}|+|\sqrt{5}-\sqrt{20}|$

$\displaystyle =|1-\sqrt{5}+\sqrt{5}-\sqrt{20}|$

$\displaystyle =|1-\sqrt{20}|$

$\displaystyle =1-\sqrt{20}$ or $\displaystyle \sqrt{20}-1$

Since it must be positive , then take $\displaystyle \sqrt{20}-1$