2(x+y)(x+y)-(x-y)²+(x-y)²
=2(x+y)²-[(x-y)²-(x-y)²]
=2(x²+2xy+y²)-0
=2x²+4xy+2y²
当x=2,y=1/2时,
原式=2×2²+4×2×½+2×(½)²
=8+4+½
=12.5
2(x+y)(x+y)-(x-y)²+(x-y)²
=2(x+y)²-[(x-y)²-(x-y)²]
=2(x²+2xy+y²)-0
=2x²+4xy+2y²
当x=2,y=1/2时,
原式=2×2²+4×2×½+2×(½)²
=8+4+½
=12.5