NECO Mathematics Past Questions & Answers - Page 37

181.

If s = \(\sqrt{(\frac{a^2}{x^2} - \frac{b^2}{y^2})}\)what does y equal?

A.

\(\sqrt{\frac{(b^2 - a^2)}{(s^2 - x^2)}}\)

B.

\(\sqrt{\frac{(b^2 - a^2)}{(s^2 \times 2)}}\)

C.

\(\sqrt{\frac{x^2 - a^2 - b^2}{s}}\)

D.

\(\frac{x^2 - a^2 - b^2}{s}\)

E.

\(\sqrt{\frac{(b^2 x^2)}{(a^2 - s^2 x^2)}}\)

Correct answer is E

s = \(\sqrt{(\frac{a^2}{x^2} - \frac{b^2}{y^2})}\)

s\(^2\) = \(\frac{a^2}{x^2} - \frac{b^2}{y^2}\)

\(\frac{b^2}{y^2}\) = \(\frac{a^2}{x^2}\) - s\(^2\)

\(\frac{b^2}{y^2}\) = \(\frac{a^2 - s^2 x^2}{x^2}\)

\(\frac{1}{y^2}\) = \((\frac{a^2 - s^2 x^2}{x^2}) \times \frac{1}{b^2}\)

\(\frac{1}{y^2}\) = \(\frac{a^2 - s^2 x^2}{b^2 x^2}\)

\(\therefore\) y\(^2\) = \(\frac{b^2 x^2}{a^2 - s^2 x^2}\)

y = \(\sqrt{\frac{b^2 x^2}{a^2 - s^2 x^2}}\)