Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 6 - Section 6.2 - Adding and Subtracting Rational Expressions - Exercise Set - Page 428: 79

Answer

$T(x)=\frac{720x+48050}{(x+70)(x+65)}$. $T(0)=11$.

Work Step by Step

The given function is $\Rightarrow T(x)=\frac{470}{x+70}+\frac{250}{x+65}$. The LCD of the denominators is $(x+70)(x+65)$. Multiply the numerators and the denominators $\Rightarrow T(x)=\frac{470(x+65)}{(x+70)(x+65)}+\frac{250(x+70)}{(x+70)(x+65)}$ Add both numerators because denominators are equal. $\Rightarrow T(x)=\frac{470(x+65)+250(x+70)}{(x+70)(x+65)}$ $\Rightarrow T(x)=\frac{470x+30550+250x+17500}{(x+70)(x+65)}$ Add like terms. $\Rightarrow T(x)=\frac{720x+48050}{(x+70)(x+65)}$ Replace $x$ with $0$. $\Rightarrow T(0)=\frac{720(0)+48050}{(0+70)(0+65)}$ Simplify. $\Rightarrow T(0)=\frac{48050}{(70)(65)}$ $\Rightarrow T(0)=\frac{48050}{4550}$ $\Rightarrow T(0)=10.5604395604$ Rounded to the nearest hour. $\Rightarrow T(0)=11$
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