Identify Integral: Let's first identify the integral we need to evaluate:I=∫−5xcos(5x+5)dxWe can use integration by parts, which states that ∫udv=uv−∫vdu, where u is a function of x, and dv is the differential of another function of x.Let's choose u=−5x (which will be differentiated) and dv=cos(5x+5)dx (which will be integrated).
Choose u and dv: Differentiate u with respect to x to find du: u=−5x du=−5dx
Differentiate u: Integrate dv to find v: dv=cos(5x+5)dx To integrate dv, we need to use the substitution method. Let w=5x+5, then dw=5dx, which means dx=5dw. v=∫cos(w)5dw v=51sin(w)+C Since w=5x+5, we substitute back to get v in terms of dv2: dv3
Integrate dv: Now apply the integration by parts formula:I=uv−∫vduI=(−5x)(51)sin(5x+5)−∫(51)sin(5x+5)(−5)dxSimplify the expression:I=−xsin(5x+5)+∫sin(5x+5)dx
Apply Integration by Parts: Now we need to integrate ∫sin(5x+5)dx. We will use the substitution method again with w=5x+5, dw=5dx, and dx=5dw.I=−xsin(5x+5)+51∫sin(w)dwIntegrate sin(w) with respect to w:I=−xsin(5x+5)+51(−cos(w))+CSubstitute back w=5x+5 to get the integral in terms of x:w=5x+50
More problems from Find indefinite integrals using the substitution and by parts