Most Important Selected Qs for JEE AdvancedMathematicsTrigonometry
Set of values of x of the equation 2 x= ( ^3 x- ^3 x ) is -
Options
- Ax , x = n + 4 ., n I
- Bx x =2 n , n I
- Cx , x =2 n + 2 ., n I
- Dx , x = n - 4 ., n I
Correct answer
C. x , x =2 n + 2 ., n I
Step-by-step solution
aligned & ^2 x- ^2 x=( x- x)(1+ x x) & x- x=0 or x+ x=1+ x x & x= x & or ( x+ x)=1+ ( x+ x)^2-1 2 & x =1 & Let x+ x=t & x = n + 4 , n I t =1+ t ^2-1 2 & t ^2-2 t +1=0 & t =1 & x+ x=1 & x 1 2 + x 1 2 = 1 2 & (x- 4 )= 4 & x - 4 =2 n 4 & X =2 n + 2 & x=2 n aligned