Question

F(x) = 3 + 5x to the second power - x + 5, 2f(3-) - f(4) =

Answer 1

the given equation is

`f(x)=3x^2-x+5`

calculate f(-3) by putting x = -3

`\begin{gathered} f(-3)=3(-3)^2-(-3)+5 \\ f(-3)=27+3+5=35 \\ \end{gathered}`

now, f(4)

`\begin{gathered} f(4)=3(4)^2-4+5 \\ f(4)=48+1=49 \end{gathered}`

now the final calculation

`\begin{gathered} 2f(-3)-f(4) \\ 2*35-49 \\ 70-49 \end{gathered}`

that is 70 -49 = 21

so the correct answer is 21

2f(-3) - f(4) =​ 21 .