(1) (2mx²+5x²+3x+1)-(7x²-4y²+3x)化简后不含x²项.
=(2m-2)x²+4y²+1
2m-2=0 m=1
(2)2m³-[3m³-(4m-5)+m]
=2-[3-(4-5)+1]
=-3