-8x2-26x-15=0

Solution for -8x2-26x-15=0 equation:

-8x^2-26x-15=0

a = -8; b = -26; c = -15;
Δ = b2-4ac
Δ = -262-4·(-8)·(-15)
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-26)-14}{2*-8}=\frac{12}{-16}
=-3/4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-26)+14}{2*-8}=\frac{40}{-16}
=-2+1/2
$