Question 579159
9+6k-8k^2
=-8k^2+6k+9
-8*9=-72; +12 and -6 are factors of -72 whose sum is +6.
-8k^2+12k-6k+9
=-4k(2k-3)-3(2k-3)  Factoring by grouping
= -(4k+3)(2k-3)
.
Ed