已知a-2b=2(a≠0),求(a²-4b²)/(a²-4b²+a+2b)-a²+4ab-4b²的值.
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![已知a-2b=2(a≠0),求(a²-4b²)/(a²-4b²+a+2b)-a²+4ab-4b²的值.](/uploads/image/z/244963-19-3.jpg?t=%E5%B7%B2%E7%9F%A5a-2b%3D2%28a%E2%89%A00%29%2C%E6%B1%82%28a%26%23178%3B-4b%26%23178%3B%29%2F%28a%26%23178%3B-4b%26%23178%3B%2Ba%2B2b%29-a%26%23178%3B%2B4ab-4b%26%23178%3B%E7%9A%84%E5%80%BC.)
已知a-2b=2(a≠0),求(a²-4b²)/(a²-4b²+a+2b)-a²+4ab-4b²的值.
已知a-2b=2(a≠0),求(a²-4b²)/(a²-4b²+a+2b)-a²+4ab-4b²的值.
已知a-2b=2(a≠0),求(a²-4b²)/(a²-4b²+a+2b)-a²+4ab-4b²的值.
已知a-2b=2(a≠0),
(a²-4b²)/(a²-4b²+a+2b)-a²+4ab-4b²
= (a+2b)(a-2b) / (a-2b)(a+2b) + (a+2b) - (a-2b) ²
= (a+2b)(a-2b) / (a-2b+1)(a+2b) - (a-2b) ²
= (a-2b) / (a-2b+1) - (a-2b) ²
代入 a-2b=2
= 2 /( 2+1) - 2x2
= 2/3 -4
= - 10/3
=-3分之10
解:原式=[(a+2b)(a-2b)]/[(a+2b)(a-2b)+a+2b)-(a-2b)^2=2/(2+1)-2^2=2/3-4=-10/3