Identify Integral: Identify the integral to be solved.We need to evaluate the integral of the function (1+x2)23xtan−1x with respect to x. This is an indefinite integral, and we will look for a substitution that simplifies the integral.
Choose Substitution: Choose a substitution.Let u=tan−1x, which implies that x=tan(u). Then, we need to find dx in terms of du. To do this, we differentiate both sides with respect to u to get dudx=sec2(u). Therefore, dx=sec2(u)du.
Rewrite in terms of u: Rewrite the integral in terms of u.Substituting x=tan(u) and dx=sec2(u)du into the integral, we get:∫(1+x2)23xtan−1xdx=∫(1+tan2(u))23tan(u)⋅u⋅sec2(u)du.Since 1+tan2(u)=sec2(u), the integral simplifies to:∫sec3(u)tan(u)⋅u⋅sec2(u)du=∫tan(u)⋅u⋅sec−1(u)du.
Simplify Further: Simplify the integral further.Since sec(u)=cos(u)1 and tan(u)=cos(u)sin(u), we can rewrite the integral as:∫(cos(u)sin(u)⋅u)⋅cos(u)du=∫u⋅sin(u)du.Now we have an integral that can be solved using integration by parts.
Apply Integration by Parts: Apply integration by parts.Let's use the formula for integration by parts: ∫udv=uv−∫vdu. We choose u=u and dv=sin(u)du, which gives us du=du and v=−cos(u).Applying integration by parts, we get:∫usin(u)du=−ucos(u)−∫(−cos(u))du=−ucos(u)+∫cos(u)du.
Integrate cos(u): Integrate cos(u). The integral of cos(u) with respect to u is sin(u), so we have: ∫u⋅sin(u)du=−u⋅cos(u)+sin(u)+C, where C is the constant of integration.
Convert to x: Convert back to x.We need to express our result in terms of x. Since u=tan−1x and cos(u)=1+x21, we have:−u⋅cos(u)+sin(u)+C=−tan−1x⋅1+x21+1+x2⋅1+x21+C.This simplifies to:−1+x2tan−1x+1+C.
Write Final Answer: Write the final answer.The integral of (1+x2)23xtan−1x with respect to x is:−1+x2tan−1x+1+C.
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