## Precalculus (6th Edition) Blitzer

The value of $g\left( f\left( -1 \right) \right)$ by the use of the function $f\left( x \right)={{x}^{2}}-x-4$ and $g\left( x \right)=2x-6$ is $-\underline{\mathsf{1}0}$.
Now, calculate $g\left( f\left( -1 \right) \right)$ by substituting x with $f\left( -1 \right)$: $x\to f\left( -1 \right)$ \begin{align} & g\left( f\left( -1 \right) \right)=2\left\{ f\left( -1 \right) \right\}-6 \\ & =2\left\{ {{\left( -1 \right)}^{2}}-\left( -1 \right)-4 \right\}-6 \\ & =2\left( 1+1-4 \right)-6 \\ & =2\left( -2 \right)-6 \end{align} \begin{align} & =-4-6 \\ & =-10 \\ \end{align} Therefore, $g\left( f\left( -1 \right) \right)=-10$. Hence, the value of $g\left( f\left( -1 \right) \right)$ by the use of the function $f\left( x \right)={{x}^{2}}-x-4$ and $g\left( x \right)=2x-6$ is $-\underline{\mathsf{1}0}$.