Question

已知多项式(2mx²-x²+3x+1)-(5x²-4y²+3x)化简后不含x&s

Answer 1

(2mx^2-x^2+3x+1)-(5x^2-4y^2+3x)

=2mx^2-x^2+3x+1-5x^2+4y^2-3x

=2mx^2-6x^2+4y^2+1

由题意可知：

2mx^2-6x^2=0

m=3

2m^2-〔3m^2+(4m-5)+m)

=2m^2-3m^2-4m+5-m

=-m^2-5m+5

代入得：

-3^2-5*3+5

=-9-15+5

=-19