2(x-y)(x+y)-(2x-y)(x+2y)
=2(x²-y²)-(2x²+4xy-xy-2y²)
=2x²-2y²-2x²-3xy+2y²
=-3xy
=-3*0.25*(-4)
=3
2(x-y)(x y)-(2x-y)(x 2y),x=0.25,y=-4
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