Identify Integral: Identify the integral to be solved.We need to evaluate the integral of the function −x4∗e−3x with respect to x.I=∫−x4∗e−3xdx
Apply Integration by Parts: Apply integration by parts.Integration by parts formula is ∫udv=uv−∫vdu, where u and dv are parts of the integrand.Let's choose u=−x4 (so that du=−4x3dx) and dv=e−3xdx (so that v=−31e−3x after integrating).
Differentiate and Integrate: Differentiate u and integrate dv.Differentiate u to find du:u=−x4du=−4x3dxIntegrate dv to find v:dv=e(−3x)dxv=−31e(−3x)
Apply Integration by Parts: Apply the integration by parts formula.Now we can apply the integration by parts formula:I=uv−∫vduI=(−x4)∗(−1/3e−3x)−∫(−1/3e−3x)∗(−4x3)dxI=(1/3)x4∗e−3x−∫34x3∗e−3xdx
Repeat Integration by Parts: Repeat integration by parts for the remaining integral.We need to apply integration by parts again to the integral ∫34x3e−3xdx.Let's choose u=x3 (so that du=3x2dx) and dv=34e−3xdx (so that v=−94e−3x after integrating).
Differentiate and Integrate: Differentiate u and integrate dv for the second application of integration by parts.Differentiate u to find du:u=x3du=3x2dxIntegrate dv to find v:dv=34e−3xdxv=−94e−3x
Apply Integration by Parts: Apply the integration by parts formula for the second time.Now we can apply the integration by parts formula again:I=31x4⋅e−3x−(9x3⋅(−4e−3x)−∫(−94e−3x)⋅(3x2)dxI=31x4⋅e−3x+94x3⋅e−3x−∫−34x2⋅e−3xdx
Notice Pattern: Notice a pattern and generalize the integration by parts.We can see a pattern emerging. Each time we apply integration by parts, the power of x decreases by one, and we get a new integral with the next lower power of x. We can continue this process until we reach the integral of a constant times e−3x, which can be integrated directly.
Continue Integration by Parts: Continue the pattern until the power of x is zero.Following the pattern, we would continue with integration by parts until we reach the integral of e−3x, which is −31e−3x. However, to avoid an excessively long solution, we will not write out all the steps. Instead, we will summarize the result of this repeated integration by parts process.
Write Final Result: Write the final result with the constant of integration.The final result of the repeated integration by parts, including the constant of integration C, is:I=(31)x4⋅e(−3x)+(94)x3⋅e(−3x)−(94)x2⋅e(−3x)⋅(32)+(278)x⋅e(−3x)−(278)⋅e(−3x)⋅(31)+CSimplifying, we get:I=(31)x4⋅e(−3x)+(94)x3⋅e(−3x)−(278)x2⋅e(−3x)+(278)x⋅e(−3x)−(818)⋅e(−3x)+C
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