Question

初一数学题。求解，急急急高分！

其中X+Y=4,XY=-3 求式子（2X-Y)-(-3Y+XY-1)的值。

Answer 1

运用整体代入法，先把式子化为X+Y和XY，在把4和3带入，最后在求值
即：
解：原式= x+y=4
xy=-3

（2x-y)-(-3y+xy-1)
=2x-y+3y-xy+1
=2x+2y-xy+1
=2(x+y)-xy+1
=2*4-(-3)+1
=8+3+1
=12

Answer 2

（2X-Y)-(-3Y+XY-1)
=2X-Y+3Y-XY+1
=2X+2Y-XY+1
=2(X+Y)-XY+1
当X+Y=4,XY=-3 时
原式=2*4+3+1=12

Answer 3

解：(2x-y)-(-3y+xy-1)
=2x-y+3y-xy+1
=2x+2y-xy+1
=2(x+y)-xy+1 代入x+y=4 xy=-3
=2×4-(-3)+1
=8+3+1=12

Answer 4

x+y=4
xy=-3

（2x-y)-(-3y+xy-1)
=2x-y+3y-xy+1
=2x+2y-xy+1
=2(x+y)-xy+1
=2*4-(-3)+1
=8+3+1
=12

Answer 5

（2X-Y)-(-3Y+XY-1)
＝2X-Y+3Y-XY+1
＝2X+2Y-XY+1
＝2*4+3+1
＝12