(a+b)²=12,(a-b)²=4,求(3a-b)²-(2a-b)²+5a(b-a)的值
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![(a+b)²=12,(a-b)²=4,求(3a-b)²-(2a-b)²+5a(b-a)的值](/uploads/image/z/1998196-52-6.jpg?t=%28a%2Bb%29%26%23178%3B%3D12%2C%EF%BC%88a-b%EF%BC%89%26%23178%3B%3D4%2C%E6%B1%82%EF%BC%883a-b%EF%BC%89%26%23178%3B-%EF%BC%882a-b%EF%BC%89%26%23178%3B%2B5a%EF%BC%88b-a%EF%BC%89%E7%9A%84%E5%80%BC)
(a+b)²=12,(a-b)²=4,求(3a-b)²-(2a-b)²+5a(b-a)的值
(a+b)²=12,(a-b)²=4,求(3a-b)²-(2a-b)²+5a(b-a)的值
(a+b)²=12,(a-b)²=4,求(3a-b)²-(2a-b)²+5a(b-a)的值
(3a-b)²-(2a-b)²+5a(b-a)的值
=9a²-6ab+b²-(4a²-4ab+b²)+5ab-5a²
=9a²-6ab+b²-4a²+4ab-b²+5ab-5a²
=3ab
=[(a+b)²-(a-b)²]/4
=(12-4)/4
=2
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