Use Integration by Parts: Let's use integration by parts to solve the integral of −xe−2x with respect to x. Integration by parts is given by the formula ∫udv=uv−∫vdu, where u and dv are parts of the integrand that we choose. We will let u=−x and dv=e−2xdx. Then we need to find du and v.
Find du: First, we differentiate u to find du. Since u=−x, we have du=−dx.
Find v: Next, we integrate dv to find v. Since dv=e−2xdx, we have v=∫e−2xdx. To integrate e−2x, we use the fact that ∫eaxdx=a1eax+C, where a is a constant. Therefore, v=(−21)e−2x.
Apply Integration by Parts Formula: Now we apply the integration by parts formula: ∫udv=uv−∫vdu. Substituting the values we found, we get ∫−xe−2xdx=uv−∫vdu=(−x)(−21)e−2x−∫(−21)e−2x(−dx).
Simplify the Integral: Simplify the integral: ∫−xe−2xdx=21xe−2x−∫21e−2xdx.
Integrate (1/2)e−2x: Now we need to integrate (1/2)e−2x with respect to x. As before, we use the fact that ∫eaxdx=(1/a)eax+C. So, ∫(1/2)e−2xdx=(1/2)(−1/2)e−2x=(−1/4)e−2x+C.
Combine Terms: Combine the terms to get the final answer: ∫−xe−2xdx=(21)xe−2x−(4−1e−2x+C).
Final Answer: Simplify the expression to get the final answer: ∫−xe−2xdx=(21)xe−2x+(41)e−2x+C.
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