(2x-y-15)² 化简

(2x-y-15)² 化简
(2x-y-15)² 化简

(2x-y-15)² 化简
(2x-y-15)² 
=（2x）²+y²+(-15)²+2(2x)(-y)+2(-y)(-15)+2(2x)(-15)
=4x²+y²+225-4xy+30y-60x
=4x²-60x+y²+30y-4xy+225
、

=（2x-y）²-2(2x-y)×15+225=4x²-4xy+y²-60x+30y+225

(2x-y-15)²
=4x²+y²+225-4xy-60x+30y