First, you need to factor the trinomial.
Mulitply -14 x 6 = -84
Now think of 2 integers when multiplied give you -84 and when added give you -17.
That would be -21 and 4.
Now split your middle terms into -21 and 4.
6x^2 +4x -21x -14
Now factor by grouping the first 2 and the last 2 terms.
2x(3x+2)-7(3x+2)=0
(2x-7)(3x+2) = 0
Now set each set of parentheses = to 0.
2x-7=0
2x=7
x=3.5
3x+2=0
3x=-2
x=-2/3