Question

先化简，再求值：【（x+y)²-y（2x+y）-8x】÷2x，其中x=-2

Answer 1

解：
【（x+y)²-y（2x+y）-8x】÷2x
原式=（x²+2xy+y²-2xy-y²-8x）÷2x
=(x²-8x)÷2x
=x/2 - 4
若x= -2，原式的值为（-2）÷2 - 4= - 5

Answer 2

﹙x²﹢y²+2xy－2xy－y²－8x﹚÷2x＝ ﹙x²－8x﹚÷2x＝x／2－4＝﹣1－4＝-5

Answer 3

[(x+y)²-y(2x+y)-8x÷2x
=[(x+y)²-y(2x+y)-x²+x²-8x]÷2x
=[(x+y)²-(2xy+y²+x²)+x²-8x]÷2x
=[(x+y)²-(x+y)²+x²-8x]÷2x
=(x²-8x)÷2x
=(x-8)÷2
=-5

Answer 4

【（x+y)²-y（2x+y）-8x】÷2x
＝（x²+2xy+y²-2xy-y²-8x）÷2x
＝（x²-8x）÷2x
=x/2-4
=-2/2-4
=-5

Answer 5

【（x+y)²-y（2x+y）-8x】÷2x
=（x²+y²+2xy-2xy-y²-8x）÷2x
=（x²-8x）÷2x
=（x-8）÷2
=（-2-8）÷2
=-10÷2
=-5