Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 11 - Quadratic Functions and Equations - 11.1 Quadratic Equations - 11.1 Exercise Set - Page 707: 78


$ 8\%$

Work Step by Step

$ A=P(1+r)^{t}\qquad$..Substitute $7290$ for $A,\ 6250$ for $P$ and $2$ for $t$. $ 7290=6250(1+r)^{2}\qquad$..divide both sides by $6250$. $\displaystyle \frac{7290}{6250}=(1+r)^{2}\qquad$..simplify. $\displaystyle \frac{729}{625}=(1+r)^{2}$ According to the general principle of square roots: For any real number $k$ and any algebraic expression $x$ : $\text{If }x^{2}=k,\text{ then }x=\sqrt{k}\text{ or }x=-\sqrt{k}$. $ 1+r=\pm\sqrt{\frac{729}{625}}\qquad$..add $-1$ to both sides. $ 1-1+r=\pm\sqrt{\frac{729}{625}}-1\qquad$..simplify. $ r=-\displaystyle \frac{25}{25}\pm\frac{27}{25}\qquad$.. The interest rate cannot be negative, we eliminate the negative solution. $ r=-\displaystyle \frac{25}{25}+\frac{27}{25}=0.08=8\%$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.