26x+15=-8x2

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

26x+15=-8x^2

We move all terms to the left:

26x+15-(-8x^2)=0

We get rid of parentheses

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