What is f (g (x)) when f (x) = x2 + 5, and g (x) = 10 - 5x?

A) f (g (x)) = - 5x2 + 35

B) f (g (x)) = - 5x2 + 15

C) f (g (x)) = 25x2 + 105

D) f (g (x)) = 25x2 - 100x + 105

Question

Delgado

Mathematics

17 March, 11:00

What is f (g (x)) when f (x) = x2 + 5, and g (x) = 10 - 5x?

A) f (g (x)) = - 5x2 + 35

B) f (g (x)) = - 5x2 + 15

C) f (g (x)) = 25x2 + 105

D) f (g (x)) = 25x2 - 100x + 105

+5

Answers (1)

Know the Answer?

Lovey · Answer 1

D

Step-by-step explanation:

To obtain f (g (x)) substitute x = g (x) into f (x), that is

f (10 - 5x)

= (10 - 5x) ² + 5 ← expand (10 - 5x) ²

= 100 - 50x - 50x + 25x² + 5 ← collect like terms

= 25x² - 100x + 105 → D

What is f (g (x)) when f (x) = x2 + 5, and g (x) = 10 - 5x?A) f (g (x)) = - 5x2 + 35B) f (g (x)) = - 5x2 + 15C) f (g (x)) = 25x2 + 105D) f (g (x)) = 25x2 - 100x + 105

What is f (g (x)) when f (x) = x2 + 5, and g (x) = 10 - 5x?

A) f (g (x)) = - 5x2 + 35

B) f (g (x)) = - 5x2 + 15

C) f (g (x)) = 25x2 + 105

D) f (g (x)) = 25x2 - 100x + 105