Question

运用惩罚公式计算:(a-2b+3c)(a+2b-3才)

Answer 1

(a-2b+3c)(a+2b-3c)

=[a-(2b-3c)][a+(2b-3c)]

=a^2-(2b-3c)^2

=a^2-4b^2+12bc-9c^2

（2x+y）（2x-y）+（x+y）^2-2（2x^2-xy)

=（2x+y）（2x-y）+（x+y）^2-2x（2x-y)

=y（2x-y）+（x+y）^2

=2xy-y^2+x^2+2xy+y^2

=x^2+4xy