Question

Sin2x-3cos2x=4 решите уравнение

Answer 1

$sin2x-3cos^2x=4\\\\2sinx\cdot cosx-3cos^2x=4(sin^2x+cos^2x)\\\\4sin^2x-2sinx\cdot cosx+7cos^2x=0\; |:cos^2x\ne 0\\\\4tg^2x-2tgx+7=0\\\\D=4-4\cdot 4\cdot 7=-108\ \textless \ 0\; \; net\; \; net\; reshenij$