For this case we have a quadratic equation of the form:
[tex]ax ^ 2 + bx + c = 0[/tex]
Rewriting the equation we have:
[tex]3k ^ 2-4k-7 = 0[/tex]
So we have to:
[tex]a = 3\\b = -4\\c = -7[/tex]
The solutions will come from:
[tex]k = \frac {-b \pm \sqrt {b ^ 2-4 (a) (c)}} {2 (a)}[/tex]
Thus, the value of "b" is -4
Answer:
[tex]b = -4[/tex]