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Ch. R - Review of Basic Concepts
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
1장, 문제 92a

Perform all indicated operations, and write each answer with positive integer exponents. [ (x-2 + y-2)/ (x-2 - y-2) ] * [ (x+y)/(x-y) ]

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Start by rewriting the expression clearly: \(\left( \frac{x^{-2} + y^{-2}}{x^{-2} - y^{-2}} \right) \times \left( \frac{x + y}{x - y} \right)\).
Recognize that \(x^{-2} = \frac{1}{x^2}\) and \(y^{-2} = \frac{1}{y^2}\). Rewrite the numerator and denominator of the first fraction using positive exponents: \(\frac{\frac{1}{x^2} + \frac{1}{y^2}}{\frac{1}{x^2} - \frac{1}{y^2}}\).
Find a common denominator for both the numerator and denominator of the large fraction: For the numerator, combine \(\frac{1}{x^2} + \frac{1}{y^2}\) as \(\frac{y^2 + x^2}{x^2 y^2}\); for the denominator, combine \(\frac{1}{x^2} - \frac{1}{y^2}\) as \(\frac{y^2 - x^2}{x^2 y^2}\).
Rewrite the large fraction as \(\frac{\frac{y^2 + x^2}{x^2 y^2}}{\frac{y^2 - x^2}{x^2 y^2}}\). Since both numerator and denominator share the same denominator \(x^2 y^2\), simplify by multiplying the numerator by the reciprocal of the denominator: \(\frac{y^2 + x^2}{x^2 y^2} \times \frac{x^2 y^2}{y^2 - x^2} = \frac{y^2 + x^2}{y^2 - x^2}\).
Now multiply this result by the second fraction \(\frac{x + y}{x - y}\): \(\frac{y^2 + x^2}{y^2 - x^2} \times \frac{x + y}{x - y}\). Notice that \(y^2 - x^2\) can be factored as \((y - x)(y + x)\). Use this factorization to simplify the expression further, and rewrite all terms with positive exponents.

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