Question

general solution of Cos2x+Cosx-2=0​

Answer 1

Step-by-step explanation:

cos2x=cosx^2-sinx^2=2cosx^2-1

2cosx^2+cosx-3=0

2cosx^2-2cosx+3cosx-3=0

2cosx(cosx-1)+3(cosx-1)=0

(cosx-1)(2cosx+3)=0

cosx=1,(-3/2)