Question

3cos2x+2sinxsosx-5sin2x=0

Answer 1

$2cos2x+2sinxcosx-5sin2x=0 \ 2cos2x+sin2x-5sin2x=0 \ 2cos2x-4sin2x=0 \ 2cos2x=4sin2x(:cos2x) \ 4tg2x=2 \ tg2x=1/2 \ 2x=arctg(1/2)+ pi k (:2) \ x= frac{1}{2} arctg1/2+ frac{ pi }{2}k$
x=1/2arctg(1/2)+(pi/2)k, k∈Z