Does anyone know how to solve the second half of this question?

see explanation

Step-by-step explanation:

given

f'(x) = 12cos x - 4sin x, then

f'() = 12cos() - 4sin()

[ cos() = -cos(), sin( = - sin() ]

= -12cos() + 4sin()

= - 12 × + 4 ×

= - 6 + 2 ≈ - 2.536 ( 3 dec. places )

step-by-step explanation:

the multiplicative inverse of a fraction a/b is b/a. for the multiplicative inverse of a real number, divide 1 by the number. for example, the reciprocal of 5 is one fifth 1/5 or 0.2, and the reciprocal of 0.25 is 1 divided by 0.25, or 4.