计算,(x-3y)(x+3y)-(x-3y)^2112^2-113×111(2x-3)(x+4)

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计算,(x-3y)(x+3y)-(x-3y)^2112^2-113×111(2x-3)(x+4)
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计算,(x-3y)(x+3y)-(x-3y)^2112^2-113×111(2x-3)(x+4)
计算,
(x-3y)(x+3y)-(x-3y)^2
112^2-113×111
(2x-3)(x+4)

计算,(x-3y)(x+3y)-(x-3y)^2112^2-113×111(2x-3)(x+4)
(x-3y)(x+3y)-(x-3y)^2
=x²-9y²-(x²-6xy+9y²)
=-18y²+6xy
112^2-113×111
=112²-(112+1)(112-1)
=112²-(112²-1²)
=1
(2x-3)(x+4)
=2x²+8x-3x-12
=2x²+5x-12

(x-3y)(x+3y)-(x-3y)^2
=(x-3y)(x+3y-x+3y)
=6y(x-3y)
112^2-113×111
=112^2-(112+1)×(112-1)
=112^2-(112^2-1)
=112^2-112^2+1
=1
(2x-3)(x+4)
=2x^2-3x+8x-12
=2x^2+5x-12

(x-3y)(x+3y)-(x-3y)^2
=x*2-9y^2-x^2+6xy-9Y^2
=-18y^2+6xy
112^2-113×111
=112^2-(112+1)(112-1)
=112^2-112^2+1
=1
(2x-3)(x+4)
=2x^2+5x-12