求几道有关整式加减的题目1、已知：X-Y = -1,XY=2.求：（-2XY+2X+3Y)-(3XY+2Y-2X)-(X

1.（-2XY+2X+3Y)-(3XY+2Y-2X)-(X+4Y+XY）
=-2xy+2X+3Y-3XY-2Y+2X-X-4Y-XY
=3x-3y-6xy
=3（x-y-2xy)
=3(-1-4)
=-15
2.A+B-(A-C)=B+C
=4X^2-5X+6+2-3X^2+1
=x^2-5x+9
2B+2C =2(B+C)=2x^2-10x+18
3.2(2X^2+3X-1)-（-X^2+X+1)
=4X^2+6X-2+X^2-X-1
=54X^2+5X-3
1.原式=-2XY+2X+3Y-3XY-2Y+2X-X-4Y-XY
=3X-3Y-6XY
=3（X-Y-2XY)
=3(-1-4)
=-15
2.∵B-C=(A+B)-(A-C) -----(X^2简写成X^,下同)
=(4X^-5X+6)-(-2+3X^-1)
=4X^-5X+6+2-3X^+1
=X^-5X+9
∴2B+2C=2(B+C)
=2(X^-5X+9)
=2X^-10X+18
3.2(2X^+3X-1)-（-X^+X+1)
=4X^+6X-2+X^-X-1
=5X^+5X-3