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Solve the differential equation:(D2 + 4D + 1)y = sin x . |
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Answer» (D2 + 4D + 1)y = sin x It's auxiliary equation is m2 + 4m + 1 = 0 = m2 + 4m + 4 - 4 + 1 = 0 = (m + 2)2 = 3 = m + 2 = ± √3 = m = -2 ± √3 C.F = C1e-(2 + √3)x + C2e-(2 - √3)x P.I = \(\cfrac1{D^2+4D+1}\) sin x = \(\cfrac1{-1^2+4D+1}\)sin x = \(\cfrac1{4D}\) sin x = \(\cfrac1{4}\) \(\int\) sin x (\(\because\) \(\cfrac1{D}\) f(x) = \(\int\) f(x) ) = - \(\cfrac1{4}\) cos x \(\therefore\) complete solution of given differential equation is y = C.F + P.I = C1e-(2 + √3)x + C2e-(2 - √3)x \(\cfrac{-cos\,x}4\) |
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