X减Y等于3,XY=1,求(负2XY加2X加3Y)减(3XY加2Y减2X)减(X加4Y加XY)的值
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X减Y等于3,XY=1,求(负2XY加2X加3Y)减(3XY加2Y减2X)减(X加4Y加XY)的值
X减Y等于3,XY=1,求(负2XY加2X加3Y)减(3XY加2Y减2X)减(X加4Y加XY)的值
X减Y等于3,XY=1,求(负2XY加2X加3Y)减(3XY加2Y减2X)减(X加4Y加XY)的值
=-2xy+2x+3y-3xy-2y+2x-x-4y-xy
=-6xy+3x-3y
=-6xy+3(x-y)
=-6+9
=3
3
(负2XY加2X加3Y)减(3XY加2Y减2X)减(X加4Y加XY)
(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)=-2xy+2x+3y-3xy-2y+2x-x-4y-xy=-6xy+3x-3y=-6*1+3(x-y)
=-6+3*3=3
把式子合并后等于负二倍的xy加三倍的x减y所以等于七
原式=(-2XY+2X+3Y)-(3XY+2Y-2X)-(X+4Y+XY)
=-2XY+2X+3Y-3XY-2Y+2X-X-4Y-XY
=-6XY+3X-3Y
=-6XY+3(X-Y)
∵X-Y=3,XY=1
∴ 代入原式=-6×1+3×3
=-6+9=3