Question

Suppose f(x) = x2 – 3x – 9 and g(x) = 2x3. What is the value ofg(8)+f(-3)?

Answer 1

We have the following functions:

`\begin{gathered} f(x)=x^2-3x-9 \\ g(x)=2x \end{gathered}`

We need to find g(8) + f(-3). The expression g(8) is equivalent to replace 8 in the place of x, that is,

`\begin{gathered} g(8)=2(8) \\ \text{then, } \\ g(8)=16 \end{gathered}`

Similarly, f(-3) is given by

`f(-3)=(-3)^2-3(-3)-9`

which gives

`\begin{gathered} f(-3)=9+9-9 \\ f(-3)=9 \end{gathered}`

Therefore, g(8)+f(-3) is given by

`g\mleft(8\mright)+f\mleft(-3\mright)=16+9`

so the answer is 25