已知多项式(2mx2-x2+3x+1)-(5x-4y+3x)化简后不含x2项,求多项式2m3-[3m3-(4m-5)+m]的值,
问题描述:
已知多项式(2mx2-x2+3x+1)-(5x-4y+3x)化简后不含x2项,求多项式2m3-[3m3-(4m-5)+m]的值,
答
(2mx2-x2+3x+1)-(5x-4y+3x)
=(2m-1)x^2-5x+1+4y
2m-1=0
m=1/2
2m3-[3m3-(4m-5)+m]
=-m^3+3m-5
=-1/8+3/2-5
=29/8
答
(2mx2-x2+3x+1)-(5x-4y+3x)
=2mx2-x2+3x+1-5x+4y-3x
=(2m-1)x2-5x+4y+1
不含x2项则2m-1=0
m=1/2
2m3-[3m3-(4m-5)+m]
=2m3-3m3+(4m-5)-m
=-m3+3m-5
=-1/8+3/2-5
=-29/8