Question

化简求值已知x=3/1,y=2/1.(3x+2y)(3x-2y)-(3x+2y)二次方+(3x-2y)二次方!

Answer 1

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

=(9x^2-4y^2)-(9x^2+12xy+4y^2)+(9x^2-12xy+4y^2)

=9x^2-4y^2-9x^2-12xy-4y^2+9x^2-12xy+4y^2

=9x^2-4y^2-24xy

当x=3/1,y=2/1

9x^2-4y^-24xy

=9*1/9-4*1/4-24*1/3*1/2

=-4