28x^2-58x-216=0

Solution for 28x^2-58x-216=0 equation:

28x^2-58x-216=0

a = 28; b = -58; c = -216;
Δ = b2-4ac
Δ = -582-4·28·(-216)
Δ = 27556
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{27556}=166$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-58)-166}{2*28}=\frac{-108}{56}
=-1+13/14
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-58)+166}{2*28}=\frac{224}{56}
=4
$