0 (\forall x \in R)" alt="\sin^2x+5\sin x\cos x+3\cos^2x=-1\\\\0=\sin^2x+5\sin x\cos x+3\cos^2 x+1=2\sin^2 x+5\sin x\cos x+4\cos^2 x=\\\\=0,5*(4\sin^2 x+10\sin x\cos x+8\cos^2 x)=\\\\=0,5*(4\sin^2x+2*2*2.5\sin x\cos x+6.25\cos^2x+1.75\cos^2 x)=\\\\=0,5*(2\sin x+2.5\cos x)^2+0.875\cos^2 x>0 (\forall x \in R)" align="absmiddle" class="latex-formula">
а) б) - решений нет