Answer:
A, 8
Step-by-step explanation:
Use the equation 15+4x=47
Subtract 15 from both sides to get
4x=32
divide to get 8
x=8
find the circumference and divide it by 10
4x^3 +10x
for f(x) × g(x) you should multiply their functions :
(2x^2+5)×(2x) = 4x^3 +10x