a²-b²=12,-a+b=-4,求:a+b
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a²-b²=12,-a+b=-4,求:a+b
a²-b²=12,-a+b=-4,求:a+b
a²-b²=12,-a+b=-4,求:a+b
-a+b=-4
a-b=4
a²-b²=12
(a+b)(a-b)=12
4(a+b)=12
a+b=3
a²-b²=12,-a+b=-4,
(a-b)(a+b)=12 a-b=4
∴a+b=3
a^2-b^2=(a+b)*(a-b)=4*(a+b)=12
所以 a+b=12/4=3
根据平方差公式得:(a-b)(a+b)=12,又由题得a-b=4.所以a+b=3