Given that a and B are both negative real numbers, the minimum value of AA + 2B + Ba + B is () A. 56B. 2(2-1)C. 22-1D. 2(2+1)

Given that a and B are both negative real numbers, the minimum value of AA + 2B + Ba + B is () A. 56B. 2(2-1)C. 22-1D. 2(2+1)

We can get AA + 2B + Ba + B = A2 + 2Ab + 2b2a2 + 3AB + 2B2 = 1-aba2 + 3AB + 2B2 = 1-1ab + 2BA + 3 by direct general division. Because a and B are all negative real numbers, AB and 2BA are all positive real numbers. The minimum value of denominator in the above formula can be obtained by using the basic inequality. The minimum value is 22, and the denominator has the minimum value, that is, 1ab + 2BA