2√3sinxcosx＋2cos²x－1
=√3(2sinxcosx)＋[2cos²x－1]
=√3sin2x＋cos2x
=2[(√3/2)sin2x＋(1/2)cos2x]
=2[sin2xcos30°＋cos2xsin30°]
=2sin(2x＋30°)