Choose u and dv: Let's use integration by parts to solve the integral of the form ∫udv. We can choose u=−4x and dv=sin(4x+5)dx. Then we need to find du and v. u=−4x implies du=−4dx To find v, we integrate dv: dv1 To integrate dv2, we use a substitution. Let dv3, then dv4, or dv5. dv6 dv7 Now we substitute back dv3: dv9
Integrate dv to find v: Now we apply the integration by parts formula:∫udv=uv−∫vduPlugging in our u, v, du, and dv, we get:∫(−4x)sin(4x+5)dx=−4x⋅(−41cos(4x+5))−∫(−41cos(4x+5))⋅(−4)dxSimplify the equation:∫(−4x)sin(4x+5)dx=xcos(4x+5)−∫cos(4x+5)dx
Apply integration by parts formula: Now we need to integrate cos(4x+5). We will use the same substitution as before:w=4x+5, dw=4dx, or dx=4dw.∫cos(4x+5)dx=∫cos(w)⋅(41)dwThis integral is straightforward:∫cos(w)⋅(41)dw=(41)sin(w)Substitute back w=4x+5:∫cos(4x+5)dx=(41)sin(4x+5)
Integrate cos(4x+5): Now we substitute the integral we just found back into our integration by parts formula:∫(−4x)sin(4x+5)dx=xcos(4x+5)−(41)sin(4x+5)This is the antiderivative of the function. We add the constant of integration C to complete the indefinite integral.
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