Answer:
3n^2 -5n -6 = 9 This is a quadratic Equation.
3n^2 -5n -15 = 0
It is solved with the Quadratic Formula:
n = [-b +-sqr root (b^2 - 4ac)] / 2a
a = 3
b = -5
c= -15
n = [--5 +- sqr root(25 -4*3*-15)] / 6
n = [5 +- sqr root (25 + 180) / 6
n = [5 +-sqr root (205) ] / 6
n = 5 + 14.3178210633 / 6
n1 = 19.3178210633 / 6
n1= 3.2196368439
n2= 5 - 14.3178210633 / 6
n2 = -9.3178210633 / 6
n2 = -1.5529701772
Explanation: