Answer:
Below in bold.
Step-by-step explanation:
f(x) = x(18x + 4)
f(x) = 18x^2 + 4x
Antiderivative = 18 * (x^2+1)/(2 + 1) -+4x(1+1) / (1+1) + C
= 18x^3 / 3 + 4x^2 / 2 + C
= 6x^3 + 2x^2 + C.
Checking by differentiating:
f'(x) = 6*3 x^(3-1) + 2*2x^(2-1)
= 18x^2 + 4x
= x(18 -+4)
