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Find the volume of the solid generated by revolving the region bounded by the graphs of 
y=x^(2)+3 and 
y=x+9 about the 
x-axis.
The volume of the solid is 
◻ cubic units.
(Type an exact answer, using 
pi as needed.)

Find the volume of the solid generated by revolving the region bounded by the graphs of y=x2+3 y=x^{2}+3 and y=x+9 y=x+9 about the x x -axis.\newlineThe volume of the solid is \square cubic units.\newline(Type an exact answer, using π \pi as needed.)

Full solution

Q. Find the volume of the solid generated by revolving the region bounded by the graphs of y=x2+3 y=x^{2}+3 and y=x+9 y=x+9 about the x x -axis.\newlineThe volume of the solid is \square cubic units.\newline(Type an exact answer, using π \pi as needed.)
  1. Identify bounds of integration: Identify the bounds of integration by setting the equations equal to each other: x2+3=x+9x^2 + 3 = x + 9. Solve for xx: \newlinex2x6=0x^2 - x - 6 = 0\newline(x3)(x+2)=0(x - 3)(x + 2) = 0\newlinex=3,x=2x = 3, x = -2
  2. Set up integral for volume: Set up the integral for the volume using the washer method, where the outer radius R(x)R(x) is x+9x+9 and the inner radius r(x)r(x) is x2+3x^2+3:Volume=πx=2x=3[(x+9)2(x2+3)2]dx\text{Volume} = \pi \int_{x=-2}^{x=3} [(x+9)^2 - (x^2+3)^2] \, dx
  3. Expand and simplify integrand: Expand the squares and simplify the integrand:\newline(x+9)2=x2+18x+81(x+9)^2 = x^2 + 18x + 81\newline(x2+3)2=x4+6x2+9(x^2+3)^2 = x^4 + 6x^2 + 9\newlineIntegrand: (x2+18x+81)(x4+6x2+9)(x^2 + 18x + 81) - (x^4 + 6x^2 + 9)\newlineSimplify: x44x2+18x+72-x^4 - 4x^2 + 18x + 72
  4. Integrate function: Integrate the function from 2-2 to 33:23[x44x2+18x+72]dx\int_{-2}^{3}[-x^4 - 4x^2 + 18x + 72] dx = (15x543x3+9x2+72x)\left(\frac{-1}{5}x^5 - \frac{4}{3}x^3 + 9x^2 + 72x\right) from 2-2 to 33 = (15(3)543(3)3+9(3)2+72(3))(15(2)543(2)3+9(2)2+72(2))\left(\frac{-1}{5}(3)^5 - \frac{4}{3}(3)^3 + 9(3)^2 + 72(3)\right) - \left(\frac{-1}{5}(-2)^5 - \frac{4}{3}(-2)^3 + 9(-2)^2 + 72(-2)\right) = 48.636+81+216-48.6 - 36 + 81 + 216 - 6.4+10.67+361446.4 + 10.67 + 36 - 144 = 212.4212.4 - 91.07-91.07 = 303.47303.47

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