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int((sin 2x)/(cos^(4)2x)+(1)/((2x+1)ln(2x+1)))dx=

(sin2xcos42x+1(2x+1)ln(2x+1))dx= \int\left(\frac{\sin 2 x}{\cos ^{4} 2 x}+\frac{1}{(2 x+1) \ln (2 x+1)}\right) d x=

Full solution

Q. (sin2xcos42x+1(2x+1)ln(2x+1))dx= \int\left(\frac{\sin 2 x}{\cos ^{4} 2 x}+\frac{1}{(2 x+1) \ln (2 x+1)}\right) d x=
  1. Split Integral: First, let's split the integral into two parts:\newline\int\left(\frac{\sin \(2\)x}{\cos^{\(4\)}\(2\)x} + \frac{\(1\)}{(\(2\)x+\(1\))\ln(\(2\)x+\(1\))}\right)dx = \int\frac{\sin \(2\)x}{\cos^{\(4\)}\(2\)x}dx + \int\frac{\(1\)}{(\(2\)x+\(1\))\ln(\(2\)x+\(1\))}dx
  2. First Integral: Now, let's tackle the first integral \(\int\frac{\sin 2x}{\cos^{4}2x}\,dx. We can use a substitution: let u=cos(2x)u = \cos(2x), then du=2sin(2x)dxdu = -2\sin(2x)\,dx. So, 12du=sin(2x)dx-\frac{1}{2} du = \sin(2x)\,dx.
  3. Substitution for First Integral: Substitute into the integral:\newlinesin2xcos42xdx=12duu4=12u4du\int\frac{\sin 2x}{\cos^{4}2x}\,dx = \int\frac{-\frac{1}{2} du}{u^{4}} = -\frac{1}{2} \int u^{-4}\,du
  4. Integration of First Integral: Now, integrate u4u^{-4} with respect to uu: 12u4du=12(13)u3=16u3-\frac{1}{2} \int u^{-4}\,du = -\frac{1}{2} \cdot \left(-\frac{1}{3}\right)u^{-3} = \frac{1}{6}u^{-3}
  5. Replace uu in First Integral: Replace uu with cos(2x)\cos(2x) to get back to xx:16u3=16(cos(2x))3\frac{1}{6}u^{-3} = \frac{1}{6}(\cos(2x))^{-3}
  6. Second Integral: Now, let's look at the second integral 1(2x+1)ln(2x+1)dx\int \frac{1}{(2x+1)\ln(2x+1)}\,dx. This one is tricky, but we can use another substitution: let v=ln(2x+1)v = \ln(2x+1), then dv=1(2x+1)dxdv = \frac{1}{(2x+1)}dx.
  7. Substitution for Second Integral: Substitute into the integral:\newline1(2x+1)ln(2x+1)dx=1vdv\int \frac{1}{(2x+1)\ln(2x+1)}\,dx = \int \frac{1}{v} \,dv
  8. Integration of Second Integral: Now, integrate 1/v1/v with respect to vv: 1vdv=lnv\int \frac{1}{v} \, dv = \ln|v|
  9. Replace vv in Second Integral: Replace vv with ln(2x+1)\ln(2x+1) to get back to xx:lnv=lnln(2x+1)\ln|v| = \ln|\ln(2x+1)|
  10. Combine Results: Combine the results from both integrals: \int\left(\frac{\sin \(2\)x}{\cos^{\(4\)}\(2\)x} + \frac{\(1\)}{(\(2\)x+\(1\))\ln(\(2\)x+\(1\))}\right)dx = \frac{\(1\)}{\(6\)}(\cos(\(2x))^{3-3} + \ln|\ln(22x+11)| + C

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