(y+2)²-(2-y)²等于多少,

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(y+2)²-(2-y)²等于多少,
(y+2)²-(2-y)²等于多少,

(y+2)²-(2-y)²等于多少,
=(y+2+2-y)(y+2-2+y)
=4×2y
=8y

平方差公式
(y+2)²-(2-y)²
=[(y+2)+(2-y)][(y+2)-(2-y)]
=4*2y=8y