It might be -3 because 3•-3 is -9?
Answer:

Step-by-step explanation:
Complete question

Required
Solve for x
We have:

Collect like terms

Multiply through by 

Make x the subject

Answer:
f(5) = 26.672 which is option D
Step-by-step explanation:
From question, f(1) = 2 and f'(x)=√(x^3 + 6)
f(5) = f(1) + (5,1)∫ f'(x) dx
Integrating using the boundary 5 and 1;
f(5) = 2 + (5,1)∫√(x^3 + 6) dx
f(5) = 2 + 24.672
So f(5) = 26.672
V(cylinder)= πr²h
d=2r,
d is diameter, r is radius.
When diameter is tripled, a new diameter D=3d,
new radius R=3d/2=(3*2r)/2=3r
R=3r
V(new cylinder)= πR²h = π(3r)²h=9πr²h
V(new cylinder)/V(cylinder)=9πr²h/πr²h=9
Volume new cylinder 9 times more the volume of old cylinder.