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121+2ln(x)(1+ln(x))2xdx\int_{1}^{2}\frac{1+2\ln(x)}{(1+\ln(x))^{2}x}\,dx

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Q. 121+2ln(x)(1+ln(x))2xdx\int_{1}^{2}\frac{1+2\ln(x)}{(1+\ln(x))^{2}x}\,dx
  1. Identify Substitution: Let's start by identifying a substitution that will simplify the integral. We can let u=1+ln(x)u = 1 + \ln(x), which implies that du=(1x)dxdu = (\frac{1}{x}) dx. This substitution will simplify the integral significantly.
  2. Find Limits for uu: Now, we need to find the corresponding limits of integration for uu. When x=1x = 1, u=1+ln(1)=1u = 1 + \ln(1) = 1. When x=2x = 2, u=1+ln(2)u = 1 + \ln(2). So, the new limits of integration are from u=1u = 1 to u=1+ln(2)u = 1 + \ln(2).
  3. Substitute uu into Integral: Substitute u=1+ln(x)u = 1 + \ln(x) and du=(1x)dxdu = (\frac{1}{x}) dx into the integral. The integral becomes:\newline1+2ln(x)(1+ln(x))2xdx=1+2(u1)u2du\int \frac{1+2\ln(x)}{(1+\ln(x))^2\cdot x} dx = \int \frac{1+2(u-1)}{u^2} du
  4. Simplify Integral: Simplify the integral: \int\left(\frac{11+22(u1-1)}{u^22}\right) du = \int\left(\frac{11+22u2-2}{u^22}\right) du = \int\left(\frac{11}{u^22} + \frac{22u}{u^22} - \frac{22}{u^22}\right) du = \int\left(\frac{11}{u^22} + \frac{22}{u} - \frac{22}{u^22}\right) du = \int\left(\frac{22}{u} - \frac{11}{u^22}\right) du
  5. Integrate Term by Term: Now, integrate term by term: (2u1u2)du=2(1u)du(1u2)du=2lnu(1u)+C\int(\frac{2}{u} - \frac{1}{u^2}) du = 2\int(\frac{1}{u}) du - \int(\frac{1}{u^2}) du = 2\ln|u| - (\frac{1}{u}) + C
  6. Substitute back to x: Substitute back u=1+ln(x)u = 1 + \ln(x) to get the antiderivative in terms of x:\newline2lnu(1/u)+C=2ln1+ln(x)1/(1+ln(x))+C2\ln|u| - (1/u) + C = 2\ln|1 + \ln(x)| - 1/(1 + \ln(x)) + C
  7. Evaluate Definite Integral: Evaluate the definite integral from u=1u = 1 to u=1+ln(2)u = 1 + \ln(2):[2ln1+ln(x)11+ln(x)]x=1x=2\left[2\ln|1 + \ln(x)| - \frac{1}{1 + \ln(x)}\right]_{x = 1}^{x = 2}=(2ln(1+ln(2))11+ln(2))(2ln(1)11)= (2\ln(1 + \ln(2)) - \frac{1}{1 + \ln(2)}) - (2\ln(1) - \frac{1}{1})=(2ln(1+ln(2))11+ln(2))(01)= (2\ln(1 + \ln(2)) - \frac{1}{1 + \ln(2)}) - (0 - 1)=2ln(1+ln(2))11+ln(2))+1= 2\ln(1 + \ln(2)) - \frac{1}{1 + \ln(2))} + 1

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