Question

Let f(x)= 2x2−3x+8 What is the value of f(-4)?

Answer 1

f(-4)=52

Explanation:

We are given the function:

`f(x)=2x^2-3x+8`

We want to find f(-4), so we must substitute -4 in for x.

`f(-4)=2(-4)^2-3(-4)+8`

Solve according to PEMDAS: Parentheses, Exponents, Multiplication, Division, Addition and Subtraction.

Evaluate the exponent first.

⇒ (-4)²= -4*-4 = 16

`f(-4)=2(16)-3(-4)+8`

Multiply 2 and 16.

⇒ 2*16=32

`f(-4)=32-3(-4)+8`

Multiply -3 and -4.

⇒-3*-4=12

`f(-4)=32+12+8`

Add the three numbers together.

`f(-4)=44+8\\\\f(-4)=52`

f(-4) for the function f(x)=2x²-3x+8 is equal to 52

Answer 2

`\displaystyle f(-4) = 52`

Explanation:

We are given the function:

`f(x)=2x^2-3x+8\\`

And we are asked to find f(-4).

To find f(-4), substitute -4 for x. Therefore:

`\displaystyle \begin{aligned} f(-4) & = 2(-4)^2-3(-4)+8 \\ \\ & = 2(16) + (12) + 8 \\ \\ & = 32 +12 + 8 \\ \\ & = 52 \end{aligned}`

In conclusion:

`f(-4) = 52`