Question

整式加减（x2 -xy+y）-3（x2 +xy-2y）等于多少

需要过程

Answer 1

这题就是让你合并同类项，
（x²-xy+y）-3（x² +xy-2y）
=x²-xy+y-3x²-3xy+6y
=(x²-3x²)-(xy+3xy)+(y+6y)
=-2x²-4xy+7y

Answer 2

(x-2)^3-(y-2)^3-(x-y)^3 =[(x-2)-(y-2)][(x-2)^2+(x-2)(y-2)+(y-2)^2]-(x-y)(x^2+xy+y^2) =(x-y)(x^2-4x+4+xy-2x-2y+4+y^2-4y+4)-(x-y)(x^2+xy+y^2) =(x-y)(x^2-4x+4+xy-2x-2y+4+y^2-4y+4-x^2-xy-y^2) =(x-y)(-6x-6y+12) =-6(x-y)(x+y-2) x+y+xy+1 =(x+xy)+(y+1) =x(1+y)+(y+1) =(y+1)(x+1)