Question

3sin^2x+5cos^2x=4 помогите

Answer 1

3Sin²x + 5Cos²x = 4
3Sin²x + 3Cos²x + 2Cos²x = 4
3(Sin²x + Cos²x) + 2Cos²x = 4
3 + 2Cos²x = 4
2Cos²x = 1
$Cos ^{2}x= frac{1}{2}\\ frac{1+Cos2x}{2}= frac{1}{2}\\1+Cos2x=1\\Cos2x=0\\2x= frac{ pi }{2}+ pi n\\x= frac{ pi }{4}+ frac{ pi n}{2} ,n$∈z