问题
解答题
(1)计算:
(2)先化简,再求值:[(x+y)2-y(2x+y)-8x]÷2x,其中x=-2. |
答案
(1)原式=1-6=-5;
(2)原式=[(x+y)2-y(2x+y)-8x]÷2x
=[x2+2xy+y2-2xy-y2-8x]÷2x
=(x2-8x)÷2x
=x(x-8) 2x
=
,x-8 2
当x=-2时,原式=
=-5.-2-8 2
(1)计算:
(2)先化简,再求值:[(x+y)2-y(2x+y)-8x]÷2x,其中x=-2. |
(1)原式=1-6=-5;
(2)原式=[(x+y)2-y(2x+y)-8x]÷2x
=[x2+2xy+y2-2xy-y2-8x]÷2x
=(x2-8x)÷2x
=x(x-8) 2x
=
,x-8 2
当x=-2时,原式=
=-5.-2-8 2