Answer:
f(-4) - f(1) = -25
Step-by-step explanation:
Knowing that:
f(x) = x² + 8x - 11,
First find f(-4). To do this, substitute -4 in for every x value in the function.
f(-4) = (-4)² + 8-(4) - 11
Square 4.
f(-4) = 16 + 8-(4) - 11
Multiply 8 and -4.
f(-4) = 16 - 32 - 11
Subtract 32 from 16.
f(-4) = -16 - 11
Subtract 11 from 48.
f(-4) = -27
Now find f(1). To do this substitute 1 in for every x value in the function.
f(1) = 1² + 8(1) - 11
Square 1.
f(1) = 1 + 8(1) - 11
Multiply 8 and 1.
f(1) = 1 + 8 - 11
Add 1 and 8.
f(1) = 9 - 11
Subtract 11 from 9.
f(1) = -2
Now take the difference of the results.
f(-4) - f(1) = -27 - (-2) = -27 + 2 = -25.
