先化簡(jiǎn),再求值. (1)[(x+y)2-y(2x+y)-8x]÷2x,其中x=-2. (2)(x+3y)2+(2x+y)(x-y)
先化簡(jiǎn),再求值.
(1)[(x+y)2-y(2x+y)-8x]÷2x,其中x=-2.
(2)(x+3y)2+(2x+y)(x-y)
優(yōu)質(zhì)解答
(1)原式=(x
2+2xy+y
2-2xy-y
2-8x)÷2x=(x
2-8x)÷2x=
x-4,
當(dāng)x=-2時(shí),原式=
×(-2)-4=-5;
(2)原式=x
2+6xy+9y
2+2x
2-xy-y
2=3x
2+5xy+8y
2.
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