Problem

Find the area of the surface obtained by rotating the curve
y=1+6x2
from x=0 to x=4 about the y-axis.

Answer

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Answer

Finally, we get A=2π[92.3677], so the area of the surface obtained by rotating the curve from x=0 to x=4 about the y-axis is 581.68π.

Steps

Step 1 :The formula for the surface area of a curve y=f(x), axb, rotated about the y-axis is given by A=2πabx1+(f(x))2dx.

Step 2 :First, we need to find the derivative of the function y=1+6x2. The derivative f(x) is f(x)=12x.

Step 3 :Substitute f(x) into the formula, we get A=2π04x1+(12x)2dx.

Step 4 :Simplify the integral, we get A=2π04x1+144x2dx.

Step 5 :To solve the integral, we can use the substitution method. Let u=1+144x2, then du=288xdx and dx=du/(288x).

Step 6 :Substitute u and dx into the integral, we get A=2π1577udu/288.

Step 7 :Solve the integral, we get A=2π[2/3u3/2/288]1577.

Step 8 :Calculate the definite integral, we get A=2π[2/35773/2/2882/313/2/288].

Step 9 :Simplify the expression, we get A=2π[2/3138.562/31/288].

Step 10 :Calculate the final result, we get A=2π[92.370.0023].

Step 11 :Finally, we get A=2π[92.3677], so the area of the surface obtained by rotating the curve from x=0 to x=4 about the y-axis is 581.68π.

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