已知A=-3x²+2y²,B=-2x²+3y²,且(x+y)²=9,(x-y)²=4.求(1)A+B (2)A-B
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已知A=-3x²+2y²,B=-2x²+3y²,且(x+y)²=9,(x-y)²=4.求(1)A+B (2)A-B
已知A=-3x²+2y²,B=-2x²+3y²,且(x+y)²=9,(x-y)²=4.求(1)A+B (2)A-B
已知A=-3x²+2y²,B=-2x²+3y²,且(x+y)²=9,(x-y)²=4.求(1)A+B (2)A-B
(x+y)²=9,(x-y)²=4.
(x+y)²(x-y)²=36
(.x²-y²)²=36
x²-y²=±6
(1)A+B=(-3x²+2y²)+(-2x²+3y²)
=-3x²+2y²-2x²+3y²
=-5x²+5y²=-5(x²-y²)=±30
(2)(x+y)²=9,(x-y)²=4
x²+y²=13/2
A-B=(-3x²+2y²)-(-2x²+3y²)
=-3x²+2y²+2x²-3y²
=-x²-y²=-(x²+y²)=-13/2
+/-30 -6.5