Question

求值、急急急急！！！

A=(5m+1)(x^2)+(3n-2)xy-5x+17y
B=6(x^2)-5mxy-11x+9
当A与B的差不含二次项时，
求[(-1)^(m+n)]{-3m+4n-[(-n)^m]}

Answer 1

A=(5m+1)(x^2)+(3n-2)xy-5x+17y
B=6(x^2)-5mxy-11x+9
A-B=(5m-5)x^2+(3n-2+5m)xy+6x+17y-9
因为不含二次项
则5m-5=0 3n-2+5m=0
m=1 n=-1

[(-1)^(m+n)]{-3m+4n-[(-n)^m]}
=1*(-3-4+1)
=-6