Question

Given the following functions, find the indicated values.f(x)=8−3x(a) f(−3)   (b) f(0)  (c) f(9)

Answer 1

f(-3)=17

f(0)=8

f(9)=18

Explanation

Evaluating a function means finding the value of f(x) that corresponds to a given value of x, so we need to input the given value and operate

Step 1

given

$f(x)=8-3x$

a) f(-3)

this is when x=-3, so replace and calculate

$\begin{gathered} f(x)=8-3x \\ f(-3)=8-3(-3) \\ f(-3)=8+9=17 \\ f(-3)=17 \end{gathered}$

hence

f(-3)=17

Step 2

f(0)

so, let x= 0 ,replace and calculate

$\begin{gathered} f(x)=8-3x \\ f(0)=8-3(0)=8-0 \\ f(0)=8 \end{gathered}$

so

f(0)=8

Step 3

f(9)

finally, for x=9

so

$\begin{gathered} f(x)=8-3x \\ f(9)=8-3(9)=8-27 \\ f(9)=-18 \end{gathered}$

so

f(9)=18