given:
sin2x-cos2x
now by applying double angle formula
for sin2x
sin2x = 2sinxcosx
for cos2x
cos2x = (cosxcosx - sinxsinx)
now putting these above values in given equation
2sinxcosx - (cosxcosx - sinxsinx)
now simplifyng
2sinxcosx - cosxcosx + sinxsinx
so the right answer is
2sinxcosx - cosxcosx + sinxsinx
