Có $y=2.(\frac{\sqrt3}2.sinx+\frac{1}2.cosx)^2+2cos^2x+2cos^2x-1$$=\frac{3}2sin^2x+\frac{1}2cos^2x+\frac{\sqrt3}2sinxcosx+4cos^2x-1$
$=\frac{3}2.\frac{1-cos2x}2+\frac{9}2.\frac{1+cos2x}2+\frac{\sqrt3}4.sin2x-1$
$=\frac{3}2.cos2x+\frac{\sqrt3}4.sin2x+5$
Còn lại khá dễ rồi, bạn tự làm nha