8x^2-28x-36=0

Solution for 8x^2-28x-36=0 equation:

8x^2-28x-36=0

a = 8; b = -28; c = -36;
Δ = b2-4ac
Δ = -282-4·8·(-36)
Δ = 1936
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1936}=44$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-44}{2*8}=\frac{-16}{16}
=-1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+44}{2*8}=\frac{72}{16}
=4+1/2
$