Question

[（x+y）的平方--（x-y）的平方]除以（-4xy) (a+3b-2c)(a-3b-2c) (2分之m+2n)的平方

Answer 1

[(x+y)²-(x-y)²]/(-4xy)

=-4xy/(-4xy)

=1

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

=(a-2c)²-9b²

=a²+4c²-9b²-4ac

(m/2+2n)²-(m/2-2n)²

=4mn