The equation ` cos^8 x + b cos^4 x + 1 = 0` will have a solution if b belongs to :

The equation cos^8x+bcos^4x+1=0 will have a solution if b belongs to

The equation cos^8x+bcos^4x+1=0 will have a solution if b belongs to (A) (-oo,2] (B) [2,oo] (C) [-oo,-2] (D) none of these

The equation cos^8x+bcos^4x+1=0 will have a solution if b belongs to (A) (-oo,2] (B) [2,oo] (C) [-oo,-2] (D) none of these

The equation sin^(4) x + cos^(4) x + sin 2x + k = 0 must have real solutions if :

The equation sin^(4) x + cos^(4) x + sin 2x + k = 0 must have real solutions if :

The equation 8cosx cos2x cos4x = (sin6x)/(sinx) has a solution given by :

The equation 8cos x*cos2x*cos4x=(sin6x)/(sin x) has a solution if

For the equation cos^(-1) x + cos^(-1) 2x + pi=0 , the number of real solutions is a)1 b)2 c)0 d) oo

The equation cos^(4)x-(lambda+2)cos^(2)x-(lambda+3)=0 have a real solution if

Verify that the function y=a cos x + b sin x is a solution of the differential equation cos x(dy)/(dx)+y sin x =b