Question

计算 1、(x+3)^2+(x-3)^2-(x+3)(x-3) 2、（4-3y)^2-(4x+3y)^2 3、(p+3q

Answer 1

1、(x+3)^2+(x-3)^2-(x+3)(x-3)

=x^2+6x+9+x^2-6x+9-x^2+9

=x^2+27

2、（4-3y)^2-(4x+3y)^2

=16-24y+9y^2-16x^2-24xy-9y^2

=16-24y-16x^2-24xy

3、(p+3q-4)(p-3q+4)

=(p+(3q-4))(p-(3q-4))

=p^2-(3q-4)^2

=p^2-9q^2+24q-16

4、[(2x-3y)(2x+3y)-(x+3y)(4x-3y)]除以3xy

=[4x^2-9y^2-4x^2+3xy-12xy+9y^2] /3xy

=[-9xy] /3xy

=-3