Solution
: At first, this problem looks complex. However, with a few tricks, this problem become much easier.Step 1: Rewrite the integral by taking out a sin (x):
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(sin3(x) cos2(x))dx = ((sin2(x) cos2(x) sin(x))dxStep 2: Substitute sin2(x) = 1 - cos2(x) into the integral:
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((sin2(x) cos2(x) sin(x))dx = (1- cos2(x))(cos2(x))(sin x)dxStep 3: Multiply through and rewrite:
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(1- cos2(x))(cos2(x))(sin x)dx = (cos2(x) - cos4(x))dxStep 4: Substitute u = cos x and du = -sin x dx into the integral:
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(cos2(x) - cos4(x))dx = - (u2 - u4)duStep 5: Separate into two integrals by using the Sum Rule:
- ò (u2 - u4)du = - ò u2 du + ò u4 du
Step 6: Integrate both integrals using the Power Rule:
- òu2 du + ò u4 du = - u(2 + 1) + u(4 + 1) + C = - u3 + u5 + C
Step 7: Substitute the original values into the equation:
- u3 + u5 + C = cos5(x) - cos3(x) + C.