Chapter 7: Transcendental Functions - Section 7.3 - Exponential Functions - Exercises 7.3 - Page 392: 138

$\frac{3}{\ln2}$

$A$ = $\int_{{\,-1}}^{{\,1}}$$2^{(1-x)}$ $dx$ $A$ = $2\int_{{\,-1}}^{{\,1}}$$2^{-x}$ $dx$ $A$ = $-2(\frac{2^{-x}}{\ln2})$ $|_{{\,-1}}^{{\,1}}$ $A$ = $\frac{-2}{\ln2}[({2^{-1}})-({2^{1}})]$ $A$ = $\frac{3}{\ln2}$