Question

If f(x) = -4x + 15 and g(x) = 7.x^3 find the following.
1) g(-3) + f(-3)
2) (f-g)(2)

Answer 1

g(-3) + f(-3) = -162

(f - g)(2) = -49

Explanation:

f(x) = -4x + 15

g(x) = 7x³

1)

g(-3) + f(-3)

Evaluate g(-3) and f(-3).

g(-3) = 7(-3)³, f(-3) = -4(-3) + 15

7(-3)³ + -4(-3) + 15

Evaluate (-3) to the third power.

7(-27) + -4(-3) + 15

Multiply.

-189 + 12 + 15

Add.

-177 + 15

-162.

2)

(f - g)(2) = f(2) - g(2)

Evaluate f(2) and g(2)

f(2) = -4(2) + 15

f(2) = -8 + 15

f(2) = 7

g(2) = 7(2)³

g(2) = 7(8)

g(2) = 56

Now subtract the result of g(2) from the result of f(2)

(f - g)(2) = 7 - 56

(f - g)(2) = -49.