设实数ab满足3a²-10ab+8b²+5a-10b=0,求u=9a²+72b+2的最小值
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![设实数ab满足3a²-10ab+8b²+5a-10b=0,求u=9a²+72b+2的最小值](/uploads/image/z/3791072-56-2.jpg?t=%E8%AE%BE%E5%AE%9E%E6%95%B0ab%E6%BB%A1%E8%B6%B33a%26%23178%3B-10ab%2B8b%26%23178%3B%2B5a-10b%3D0%2C%E6%B1%82u%3D9a%26%23178%3B%2B72b%2B2%E7%9A%84%E6%9C%80%E5%B0%8F%E5%80%BC)
设实数ab满足3a²-10ab+8b²+5a-10b=0,求u=9a²+72b+2的最小值
设实数ab满足3a²-10ab+8b²+5a-10b=0,求u=9a²+72b+2的最小值
设实数ab满足3a²-10ab+8b²+5a-10b=0,求u=9a²+72b+2的最小值
(a-2b)(3a-4b)+5a-10b=0
(a-2b)(3a-4b+5)=0U=9a^2+72b+2中将a=2b或4b=3a+5带入
则当a=2b时,u=-34
当4b=3a+5时,u=11
取最小值,所以u=-34