已知xy=¼,则(x+y)²-(x-y)²的值为

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(x+y)²-(x-y)²
=x²+2xy+y²-(x²+y²-2xy)
=4xy
=4×(1/4)
=1

(x+y)²-(x-y)²
=x²+2xy+y²-x²-y²+2xy
=4xy
=4×(1/4)
=1