Split Integral: First, let's split the integral into two parts:\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
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), then du=−2sin(2x)dx. So, −21du=sin(2x)dx.
Substitution for First Integral: Substitute into the integral:∫cos42xsin2xdx=∫u4−21du=−21∫u−4du
Integration of First Integral: Now, integrate u−4 with respect to u: −21∫u−4du=−21⋅(−31)u−3=61u−3
Replace u in First Integral: Replace u with cos(2x) to get back to x:61u−3=61(cos(2x))−3
Second Integral: Now, let's look at the second integral ∫(2x+1)ln(2x+1)1dx. This one is tricky, but we can use another substitution: let v=ln(2x+1), then dv=(2x+1)1dx.
Substitution for Second Integral: Substitute into the integral:∫(2x+1)ln(2x+1)1dx=∫v1dv
Integration of Second Integral: Now, integrate 1/v with respect to v: ∫v1dv=ln∣v∣
Replace v in Second Integral: Replace v with ln(2x+1) to get back to x:ln∣v∣=ln∣ln(2x+1)∣
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} + \ln|\ln(2x+1)| + C
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