Answer
$-(x+7), \quad x\ne2$
Work Step by Step
By factoring both denominator and numerator and canceling the common factors, we obtain:
\begin{align*}
\require{cancel}
\dfrac{x^2+5x-14}{2-x}&=\dfrac{(x-2)(x+7)}{-(x-2)}\\
\\&=\dfrac{\cancel{(x-2)}(x+7)}{-\cancel{(x-2)}}\\
\\&=-(x+7), \quad x\ne2
\end{align*}