Question

Let f(x) = -­2x ­- 7 and g(x) = ­-4x + 3. Find (fog)(-­5)

Answer 1

ANSWER

$( f \circ \: g)( - 5)= -53$

EXPLANATION

The given functions are:

f(x) = -­2x ­- 7 and g(x) = ­-4x + 3

$( f \circ \: g)(x) = f(g(x))$

$( f \circ \: g)(x) = f( - 4x + 3)$

$( f \circ \: g)(x) = - 2( - 4x + 3) - 7$

Expand:

$( f \circ \: g)(x) = 8x - 6 - 7$

$( f \circ \: g)(x) = 8x - 13$

We substitute x=-5

$( f \circ \: g)( - 5) = 8( - 5) - 13 = -53$