Question

Evaluate the functions for the given input values.

f(x) = x² + 1
g(x) = 2f(x)
g(-3) =
g(2) =
g(7) =

Answer 1

g(-3) = 20

g(2) = 10

g(7) = 100

Explanation:

g(x) = 2f(x) tells us that g(x) is two times f(x). Instead of f(x) we can write (x² + 1).

g(x) = 2f(x)

g(x) = 2(x² + 1)

Multiply.

g(x) = 2x² + 2

Now that we have g(x) we just substitute values in the function.

g(-3) = 2(-3)² + 2

= 2(9) + 2

= 18 + 2

= 20

g(2) = 2(2)² + 2

= 2(4) + 2

= 8 + 2

= 10

g(7) = 2(7)² + 2

= 2(49) + 2

= 98 + 2

= 100