The roots of the equation x2+2(a−3)x+9=0 lies between -6 and 1 then [ a ] =________ , where [.] denotes greatest integer function x.
3
6
12
19
△ ≥ 0 , f(-6) > 0 , f(1) > 0 , -6 < α+β2 < 1 ⇒ [a] = 6