(1)m的平方-(m+2)(m-3);(2)(a-b)的平方+b(2a+b)(3);(x-3y)(y+3x)-(x-3y
1个回答

1)m²-(m+2)(m-3)

=m²-(m²-m-6)

=m²-m²+m-6

=m-6

2)(a-b)²+b(2a+b)

=a²-2ab+b²+2ab+b²

=a²+2b²

3)(x-3y)(y+3x)-(x-3y)(3y-x)

=(xy+3x²-3y²-9xy)+(x-3y)²

=3x²-3y²-8xy+x²+9y²-6xy

=4x²+6y²-14xy

4)(2x-y+3)(2x+y-3)

=[2x-(y-3)][2x+(y-3)]

=4x²-(y-3)²

=4x²-(y²-6y+9)

=4x²-y²+6y-9