Verified answer

x=0

x=y(y-7)

y(y-7)=0

y=0

y=7

Radius = y

height = y(7-y) = 7y-y^2

Volume = 2pi ∫ y (7y-y^2) dy

= 2pi ∫ (7y^2-y^3) dy

2pi ∫ (7y^2-y^3) dy

Integrate from 0 to 7

=2401 pi /6

Your answer is correct.

Your computer may prefer to have it entered as (2401/6)*pi or 2401*pi/6 or as a completely numerical value. Sometimes answer checkers are particular as to the forms they accept.