已知代数式3x^2-2y+6的值为8,那么代数式3xy^2-2xy-3/2y^2-2x+y+2的值为_数学解答

已知代数式3x^2-2y+6的值为8,那么代数式3xy^2-2xy-3/2y^2-2x+y+2的值为

人气：488 ℃　时间：2019-08-19 01:12:31

解答

3xy^2-2xy-3/2y^2-2x+y+2
=x(3y^2-2y)-1/2(3y^2-2y)-2x+2
=(x-1/2)(3y^2-2y)-2(x-1/2)+1
=(x-1/2)(3x^2-2y-2)+1
因为3x^2-2y+6=8
所以3x^2-2y-2=0
故：3xy^2-2xy-3/2y^2-2x+y+2=1