已知x/y=2/7,则x²-3xy+2y²/2x²-9xy+7y²的值为
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![已知x/y=2/7,则x²-3xy+2y²/2x²-9xy+7y²的值为](/uploads/image/z/1344890-2-0.jpg?t=%E5%B7%B2%E7%9F%A5x%2Fy%3D2%2F7%2C%E5%88%99x%26%23178%3B-3xy%2B2y%26%23178%3B%2F2x%26%23178%3B-9xy%2B7y%26%23178%3B%E7%9A%84%E5%80%BC%E4%B8%BA)
已知x/y=2/7,则x²-3xy+2y²/2x²-9xy+7y²的值为
已知x/y=2/7,则x²-3xy+2y²/2x²-9xy+7y²的值为
已知x/y=2/7,则x²-3xy+2y²/2x²-9xy+7y²的值为
你好!
(x²-3xy+2y²)/(2x²-9xy+7y²)
= [ (x/y)² - 3(x/y) + 2 ] / [ 2(x/y)² - 9(x/y) + 7] (分子分母同除以 y²)
= [ (2/7)² - 3×2/7 +2 ] / [ 2×(2/7)² - 9×2/7 + 7]
= (60/49) / (125/49)
= 12/25