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

User Rogergl
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1 Answer

5 votes

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

User Ann
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