4k^2-7k-36=0

Solution for 4k^2-7k-36=0 equation:

4k^2-7k-36=0

a = 4; b = -7; c = -36;
Δ = b2-4ac
Δ = -72-4·4·(-36)
Δ = 625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{625}=25$
$k_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-25}{2*4}=\frac{-18}{8}
=-2+1/4
$
$k_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+25}{2*4}=\frac{32}{8}
=4
$