Question

如多项式（2mx的平方-x的平方+5x+8）-（7x次方-3y+5X)的值与x的取值无关，求m次方-{2m次方-（5m-4)+m}的值

Answer 1

(2mx²-x²+5x+8)-(7x²-3y+5x)
=(2m-1-7)x²+3y+8
根据题意
2m-8=0
m=4
m²-[2m²-(5m-4)+m]
=-m²+5m-4+m
=-m²+6m-4
=-16+24-4
=4
关键就是化简多项式，令x的系数为0，求出m

Answer 2

2mx²-x²+5x+8)-(7x²-3y+5x)
=(2m-1-7)x²+3y+8
根据题意
2m-8=0
m=4
m²-[2m²-(5m-4)+m]
=-m²+5m-4+m
=-m²+6m-4
=-16+24-4
=4
只有当2m-8=0时，（2m-8)x平方=0×x平方=0