GMAT Math : Simplifying Algebraic Expressions

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Example Questions

Example Question #51 : Simplifying Algebraic Expressions

Assume that \(\displaystyle x,y \neq 0\).

Which of the following expressions is equal to the following expression?

\(\displaystyle \frac{(x+y)^{2} +(x - y)^{2}}{x^{2}y^{2}}\) 

Possible Answers:

\(\displaystyle \frac{2 }{x^{2}} + \frac{2 }{y^{2}}\)

\(\displaystyle 4x^{2}y^{2}\)

\(\displaystyle \frac{2 }{x} + \frac{2 }{y}\)

\(\displaystyle 4\)

\(\displaystyle \frac{2 }{x^{2}y} + \frac{2 }{xy^{2}}\)

Correct answer:

\(\displaystyle \frac{2 }{x^{2}} + \frac{2 }{y^{2}}\)

Explanation:

\(\displaystyle \frac{(x+y)^{2} +(x - y)^{2}}{x^{2}y^{2}}\)

\(\displaystyle =\frac{(x^{2}+2xy+y^{2}) + (x^{2}-2xy+y^{2}) }{x^{2}y^{2}}\)

\(\displaystyle =\frac{x^{2}+x^{2}+2xy-2xy+y^{2}+y^{2} }{x^{2}y^{2}}\)

\(\displaystyle =\frac{2x^{2}+2y^{2} }{x^{2}y^{2}}\)

\(\displaystyle =\frac{2x^{2} }{x^{2}y^{2}} + \frac{2y^{2} }{x^{2}y^{2}}\)

\(\displaystyle =\frac{2 }{y^{2}} + \frac{2 }{x^{2}} = \frac{2 }{x^{2}} + \frac{2 }{y^{2}}\)

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