Question

area of surface obtained by revovling the graph
y=x^4/4+1/8x^2 from 1 to 2?

Answer 1

revolving around the x-axis or the y-axis?

Answer 2

y axis

Answer 3

m sorry

Answer 4

Use the shell method, the volume of a shell
\[ 2\pi x\left ( \frac 9 2 -y \right)dx
\]
9/2 is for x =1

Answer 5

\[2\pi x\left ( \frac 9 2 -\frac{x^4}{4}-\frac{x^2}{8} \right)dx=\\
2\pi \left ( \frac 9 2 x -\frac{x^5}{4}-\frac{x^3}{8} \right)dx
\]
Integrate this quantity from x=1 to x=2

Answer 6

9/2 is for x=2 (correction to a previous post)

Answer 7

Your final answer should be
\[\frac{117 \pi }{16}
\]