Rewrite the expression in terms of exponentials and simplify the results.
-$14 \cosh ( \ln x )$
A) $7 \left( e ^ { x } + e ^ { - x } \right)$
B) $7 x$
C) 0
D) $7 \left( x + \frac { 1 } { x } \right)$

Question

Quizplus · Accepted Answer

Using the identity $\cosh(x)=\frac{e^{x}+e^{-x}}{2}$, we can rewrite the expression as:
$$14 \cosh(\ln x)=14\cdot \frac{e^{\ln x}+e^{-\ln x}}{2}=7(x+x^{-1})$$
which is equivalent to choice D.

Rewrite the Expression in Terms of Exponentials and Simplify the Results