MathRevolution wrote:

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Math Revolution GMAT math practice question]

If a rectangle’s length is \(a+b\) and its area is \((\frac{1}{a})+(\frac{1}{b})\), what is its width?

\(A. 1\)

\(B. a+b\)

\(C. ab\)

\(D. \frac{1}{(a+b)}\)

\(E. \frac{1}{ab}\)

Just a glance at the alternative choices makes us realize that

all of them get different values when a=b=3, hence...

Let´s explore this

PARTICULAR CASE!

\({\rm{rectangle}}\,\,\left\{ \matrix{

\,{\rm{length}} = \,\,6 \hfill \cr

\,{\rm{area}} = \,\,{2 \over 3} \hfill \cr} \right.\,\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,?\,\,\left( {{\rm{target}}} \right)\,\,\,\, = \,\,\,\,{{\,\,{2 \over 3}\,\,} \over 6}\,\, = \,\,{1 \over 9}\,\,\,\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,\,\left( E \right)\)

This solution follows the notations and rationale taught in the GMATH method.

Regards,

Fabio.

_________________

Fabio Skilnik :: https://GMATH.net (Math for the GMAT) or GMATH.com.br (Portuguese version)

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