S=pi∫a,bf(x)^2dx
1)S=1\2*pi∫1,2(x^3)^2dx=|2,1(1/2*pix^7/7)=1/14*pi(128-1)=127pi/14 (1/2 -ось х делит пополам образованное тело)
2) y=-√x y=-2x
-√x=-2x
x=4x^2
4x^2-x=0
x(4x-1)=0
x=0 4x-1=0 x=1/4
S=pi∫0,1/4(x-4x^2)dx=pi|1/4,0|(x^2/2-4x^3/3)=pi(1/32-4*1/64*3)=pi(1/32-1/16*3)=pi(3-2)|96=pi/96