86243 ∫x2+1x4−x2+1dx=
(A) : I=∫x2+1x4−x2+1dx=∫1+1x2x2−1+1x2dx=∫1+1x2(x−1x)2+1dxLet, x−1x=t(1+1x2)dx=dt∴I=∫dtt2+1=tan−1(t)+c=tan−1(x−1x)+c=tan−1(x2−1x)+c
86244 ∫abxx+a+b−xdx=
(B) : I=∫abxx+a+b−xdxI=∫aba+b−xa+b−x+a+b−(a+b−xdxI=∫aba+b−xa+b−x+xdxFrom equation (i) and equation (ii) adding, we get -2I=∫abx+a+b−xx+a+b−xdx2I=∫abdx=[x]ab=b−aI=b−a2
86245 If ∫dx16−9x2=Asin−1(Bx)+C then A+B=
(D) : Given,∫dx16−9x2=Asin−1(Bx)+CL.H.S., I=∫dx16−9x2=13∫dx(43)2−x2=13sin−13x4+COn comparing L.H.S. and R.H.S., we get-A=13, B=34∴A+B=13+34=1312
86246 ∫ex[2+sin2x1+cos2x]dx=
(A) : I=∫ex(2+sin2x1+cos2x)dx=∫ex(21+cos2x+sin2x1+cos2x)dx =∫ex(22cos2x+2sinx⋅cosx2cos2x)dx=∫ex(sec2x+tanx)dx[∵∫ex[f(x)+f′(x)]dx=exf(x)+c]=ex⋅tanx+c