Identify integral: Identify the integral that needs to be solved.We need to find the integral of the function tan−1(5x) with respect to x.∫tan−1(5x)dx
Use integration by parts: Use integration by parts.Integration by parts formula is ∫udv=uv−∫vdu, where u and dv are parts of the integrand.Let u=tan−1(5x), which means du=(1+(5x)25)dx.Let dv=dx, which means v=x.
Differentiate and integrate: Differentiate u and integrate dv.\ Differentiate u to find du:\ du=dxd[tan−1(5x)]dx=(1+(5x)25)dx\ Integrate dv to find v:\ v=∫dx=x
Apply integration by parts: Apply the integration by parts formula.Now we have u, du, v, and dv, we can apply the integration by parts formula:∫tan−1(5x)dx=uv−∫vdu= (tan−1(5x))⋅x−∫x⋅(1+(5x)25)dx
Simplify the integral: Simplify the integral.We need to simplify the integral ∫x⋅(1+(5x)25)dx.Let's make a substitution to simplify this integral. Let w=1+(5x)2, then dw=10xdx.
Change variables: Change the variables in the integral.Substitute w and dw into the integral:∫x⋅(1+(5x)25)dx=21⋅∫(w5)dwWe have the extra 21 because dw=10xdx, so we need to multiply by 101 to get the original xdx, and since we have a 5 in the numerator, 5⋅101=21.
Integrate with respect to w: Integrate with respect to w. Now integrate 21×∫(w5)dw: \frac{\(1\)}{\(2\)} \times \int\left(\frac{\(5\)}{w}\right)dw = \frac{\(1\)}{\(2\)} \times \(5 \times \ln|w| + C = \left(\frac{5}{2}\right) \times \ln|w| + C
Substitute back for x: Substitute back for x.Now we need to substitute back in for w to get the integral in terms of x:25⋅ln∣w∣+C=25⋅ln∣1+(5x)2∣+C
Combine integration results: Combine the results from integration by parts.Combine the result from Step 4 and Step 8 to get the final answer:∫tan−1(5x)dx=(tan−1(5x))⋅x−25⋅ln∣1+(5x)2∣+C
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