2a=3b2a=3b求4a²+12ab+9a²/2a²+5ab+3b²
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![2a=3b2a=3b求4a²+12ab+9a²/2a²+5ab+3b²](/uploads/image/z/6972203-11-3.jpg?t=2a%3D3b2a%3D3b%E6%B1%824a%26%23178%3B%2B12ab%2B9a%26%23178%3B%2F2a%26%23178%3B%2B5ab%2B3b%26%23178%3B)
2a=3b2a=3b求4a²+12ab+9a²/2a²+5ab+3b²
2a=3b2a=3b求4a²+12ab+9a²/2a²+5ab+3b²
2a=3b2a=3b求4a²+12ab+9a²/2a²+5ab+3b²
应该是:(4a²+12ab+9b²)/(2a²+5ab+3b²)
=(2a+3b)^2/(2a+3b)(a+b)
=(2a+3b)/(a+b)
代入:2a=3b
=(3b+3b)/(b+3b/2)
=6b/(5b/2)
=6/(5/2)
=6*2/5
=12/5
∵2a=3b,
∴a=3b/2
(4a²+12ab+9b²)/(2a²+5ab+3b²)
=(2a+3b)²/(2a+3b)(a+b)
=(2a+3b)/(a+b)
=(3b+3b)/(3b/2+b)
=6b/(5b/2)
=12/5