## Precalculus: Mathematics for Calculus, 7th Edition

$i = \pm 100\sqrt {\frac{A}{P}} - 100$
$Solve$ $the$ $equation$ $for$ $the$ $indicated$ $variable:$ $A = P(1+\frac{i}{100})^2;$ $for$ $i$ Solve for $i$ Divide both sides by $P$ $\frac{A}{P} = \frac{P(1+\frac{i}{100})^2}{P}$ $\frac{A}{P} = (1+\frac{i}{100})^2$ Square root both sides $\pm \sqrt {\frac{A}{P}} = \sqrt {(1+\frac{i}{100})^2}$ $\pm \sqrt {\frac{A}{P}} = 1+\frac{i}{100}$ Subtract 1 from both sides $\pm \sqrt {\frac{A}{P}} - 1 = 1+\frac{i}{100} -1$ $\pm \sqrt {\frac{A}{P}} - 1 = \frac{i}{100}$ Multiply both sides by 100 $100(\pm \sqrt {\frac{A}{P}} - 1) = 100(\frac{i}{100})$ $i = \pm 100\sqrt {\frac{A}{P}} - 100$