86144 ∫tan−1(1−x1+x)dx is equal to
(A) : Given,∫tan−1(1−x1+x)dxLet x=cos2θθ=cos−1x2So, I=∫tan−1(1−cos2θ1+cos2θ)dx=∫tan−11−(1−2sin2θ)1+(2cos2θ−1)dx=∫tan−1(tanθ)dx=∫θ.dx=12∫cos−1xdx=12∫1⋅cos−1xdx=12[x⋅cos−1x−∫(−11−x2)⋅xdx]=12[xcos−1x+∫x⋅dx1−x2]=12[xcos−1x−1−x2]+C
86145 ∫sinx+8cosx4sinx+6cosxdx is equal to
(A) : Given,∫sinx+8cosx4sinx+6cosxdxsinx+8cosx=Addx(4sinx+6cosx)+B(4sinx+ 6cosx)sinx+8cosx=A(4cosx−6sinx)+(4sinx+6cosx)BWe compare the equation and find the value of A and B−−6 A+4 B=14 A+6 B=8So, A=12 and B=1sinx+8cosx=12(4cosx−6sinx)+(4sinx+6cosx)∫(sinx+8cosx)dx4sinx+6cosx=12∫4cosx−6sinx4sinx+6cosxdx+∫4sinx+6cosx4sinx+6cosxdx Let,⇒4sinx+6cosx=tSo,⇒(4cosx−6sinx)dx=dt=12∫dtt+∫dx=12log|4sinx+6cosx|+x+CHence, I=x+12log(4sin+6cosx)+c
86146 If g(t+12t+1)=t+1, then ∫g(x)dx=
(D) : Given,Let,g(t+12t+1)=t+1t+12t+1=x⇒t+1=x(2t+1)t−2tx=x−1⇒t(1−2x)=x−1t=x−11−2x So, f(x)=x−11−2x+1=x−1+1−2x1−2x=x2x−1∫x2x−1dx=12∫2x−1+12x−1dx=12[∫2x−12x−1dx+∫12x−1dx]=12[∫dx+∫12x−1dx]=12[x+12log|2x−1|]+C=x2+14log|2x−1|+C
86147 ∫x8−9x2+18x4−3x2+3dx=
(C) : Given,∫x8−9x2+18x4−3x2+3dxx8−9x2+18 is divided by x4−3x2+3, we get quotient x4+3x2+6 and 0 remainder.Now, ∫(x4+3x2+6)dx=x55+3x33+6x+C=x55+x3+6x+C