(2x-y+3)*(2x-y-3)用平方差公式,(a-b+c)²完全平方公式,
问题描述：
(2x-y+3)*(2x-y-3)用平方差公式,(a-b+c)²完全平方公式,
答
1
=(2x-y)²(-3)²
=4x²-4xy+y²-9
2
=a²+b²+c²-2ab+2bc-2bc
答
(2x-y+3)*(2x-y-3)=(2x-y)^2-3^2
=4x^2-4xy-y^2-9
(a-b+c)²=a^2+b^2+c^2-2ab+2ac-2bc
答
1 (2x-y+3)*(2x-y-3)
=(2x-y)²(-3)²
=4x²-4xy+y²-9
2 (a-b+c)²
=a²+b²+c²-2ab+2bc-2bc