ABC26GN0989 · Simplification
Subject: General Aptitude · Chapter: Simplification · Exam: · Marks: · Difficulty:
If $\frac{x}{y}=\frac{a+2}{a-2}$, then $\frac{x^{2}-y^{2}}{x^{2}+y^{2}}$ is equal to
(a)$\frac{8 a}{a^{2}+4}$
(b)$\frac{4 a}{a^{2}-4}$
(c)$\frac{4}{a^{2}}$
(d)$\frac{4 a}{a^{2}+4}$
Answer
Explanation
$\frac{x^{2}-y^{2}}{x^{2}+y^{2}}=\frac{\left(\frac{x^{2}}{y^{2}}\right)-1}{\left(\frac{x^{2}}{y^{2}}\right)+1}=\frac{\left(\frac{x}{y}\right)^{2}-1}{\left(\frac{x}{y}\right)^{2}+1}=\frac{\left(\frac{a+2}{a-2}\right)^{2}-1}{\left(\frac{a+2}{a-2}\right)^{2}+1}$
Explanation as extracted from the printed page; notation may be imperfect.
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