Question

Let f(x)=4x+7 and g(x)=3x-5. find (fog)(-4)

A. -9
B. -61
C. -32
D. -17

Answer 1

B . (fog)(-4) = - 61

Explanation:

Here, given f(x) = 4 x + 7, g(x) = 3 x- 5

Now, by the COMPOSITE FUNCTION:

(f o g) (x) = f (g(x))

Now here: )f o g) ( -4) = f (g(-4))

Simplifying for g(x) = 3 x - 5

g(-4) = 3 (-4) - 5 = -12 - 5 = -17

or, g (-4) = -17

Now, for f(x) = 4 x + 7

f ( g(-4)) = f ( -17) = 4 (-17) + 7

= - 68 + 7 = - 61

or, f ( g(-4)) = - 61

Hence, (fog)(-4) = - 61