JEE Main201815 Apr 2018Evening ShiftMathematicsDefinite IntegrationActual
The value of integral _ 4 ^ 3 4 x 1+ x d x is
Options
- A2 ( 2 +1)
- B( 2 -1)
- C2 ( 2 -1)
- D2
Correct answer
A. 2 ( 2 +1)
Step-by-step solution
Let I= _ 4 ^ 3 4 x 1+ x d x also let K= x 1+ x Multiplying numerator and denominator by (1- x) , we get; aligned K &= x(1- x) 1-( x)^2 = x(1- x) ( x)^2 &=x(1- x) ^2 x &=x ^2 x-x x ^2 x=x ^2 x-x x & x aligned Now, I= _ 4 ^ 3 4 x ^2 x d x- _ 4 ^ 3 4 x x x d x = [x x- d x d x x d x ]_ 4 ^ 3 4 - [x x- d x d x x d x ]_ 4 ^ 3 4 aligned &=[x x- | x|]_ 4 ^ 3 4 &-[x x- | x+ x|]_ 4 ^ 3 4 +c & I= [ 3 4 3 4 - | 3 4 | . . & .- [ 3 4 3 4 - | 3 4 + 3 4 | ] &- [ 4 4 - | 4 | . . & .- [ 4 4 - | 4 + 4 | ] &= 2 ( 2 +1) aligned