Question

Which equation shows a correct evaluation of (mn)(4)?

m(x) = 4x-5
n(x) = 2x + 11
A.
(mn)(4) = 8(4) - 55
B.
(mn)(4) = 8(4)2 + 34(4) - 55
C.
(mn)(4) = 8(4)2 - 55
D.
(mn)(4) = 8(4)2 - 6(4) - 55

Answer 1

`(mn)(x) =8(4^2) +34(4) - 55`

Explanation:

Given

`m(x) = 4x - 5`

`n(x) = 2x + 11`

Required

What is (mn)(4)?

In functions:

`(mn)(x) = m(x) * n(x)`

Substitute values for m(x) and n(x)

`(mn)(x) = (4x - 5)(2x + 11)`

Substitute 4 for x

`(mn)(x) = (4*4 - 5)(2*4 + 11)`

`(mn)(x) = (4^2 - 5)(8 + 11)`

`(mn)(x) =8(4^2) - 8*5 + 11(4^2) - 11 * 5`

`(mn)(x) =8(4^2) - 40 + 176 - 11 * 5`

`(mn)(x) =8(4^2) +136 - 55`

`(mn)(x) =8(4^2) +34(4) - 55`