Question

Please check my work and answer. Question: what is the function for the difference of area between a sphere with radius r+1 and a sphere with radius r? One hundred points!

Answer 1

8πr + 4π

Explanation:

Your mistake in solving this problem was using the formula for volume rather than find the difference in area.

a(r) = 4πr^2

a = a(r + 1) - a(r)

a = [4π(r + 1)^2]

a = 4π(r^2 - r^2 + 2r + 1)

a = 4π(2r + 1)

a = 8πr + 4π

Best of Luck!

Answer 2

you have used the volume formula when the problem asks for a difference of area.

ΔA = 4π(2r+1) = 8πr +4π

Explanation:

A(r) = 4πr²

ΔA = A(r+1) - A(r) = (4π(r+1)²) -4πr² = 4π(r² +2r +1 - r²)

ΔA = 4π(2r +1) = 8πr +4π