If the function y = 3x2 - (9 + a) x + 6 + 2A (x is an independent variable and X is an integer) gets the minimum value when x = 6 or x = 7, then the value range of a is______ .

If the function y = 3x2 - (9 + a) x + 6 + 2A (x is an independent variable and X is an integer) gets the minimum value when x = 6 or x = 7, then the value range of a is______ .

The axis of symmetry of parabola is a straight line x = - - - - - (9 + a) 2 × 3 = 9 + A6, ∵ when x = 6 or x = 7, the minimum value is obtained, X is an integer, ∵ 9 + A6 > 5.5 ① 9 + A6 < 7.5 ②, solving inequality ①, a > 24, solving inequality ②, a < 36, so the solution of inequality group is 24 < a < 36, that is, the value range of a is 24 < a < 36