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Evaluate: ∫ 1 - x2x 1 - 2x dx
∫1 - x2x 1 - 2x dxHere 1 - x2x 1 - 2x is an improper rational fraction.
Reducing it to proper rational fraction gives
1 - x2x 1 - 2x = 12 + 12 2 - xx 1 - 2x .......(i)Now, let 2 - xx 1 - 2x = Ax + B 1 - 2x ⇒ 2 - xx 1 - 2x = A 1 - 2x + Bxx 1 - 2x ⇒ 2 - x = A - x 2A - B
Equating the coefficients we get, A = 2 and B = 3
So, 2 - xx 1 - 2x = 2x + 3 1 - 2x
Substituting in equation (i), we get
1 - x2x 1 - 2x = 12 + 12 2x + 3 1 - 2x i.e. ∫ 1 - x2x 1 - 2x dx = ∫ 12 + 12 2x + 3 1 - 2x dx = ∫ dx2 +∫ dxx + 32 ∫ dx 1 - 2x = x2 + log x + 32 x 1 - 2 log 1 - 2x + C = x2 + log x - 34 x log 1 - 2x + C.
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