Question

Cos2x+3корня из 3 sin(3п/2+x)-5=0

Answer 1

Cos2x-3√3cosx-5=0
2cos^2x-1-3√3cosx-5=0
2cos^2x-3√3cosx-6=0
Замена cosx=a, a∈[- 1;1]
2a^2-3√3a-6=0
D=27+48=75
√D=5√3
a1=- √3/2
a2=2√3∉[ - 1; 1]
cosx = - √3/2
x=+- (π-π/6)+2πn, n∈Z
x=+- 5π/6 + 2πn, n∈Z