0=2r^2+10r+8

Solution for 0=2r^2+10r+8 equation:

0=2r^2+10r+8

We move all terms to the left:

0-(2r^2+10r+8)=0

We add all the numbers together, and all the variables

-(2r^2+10r+8)=0

We get rid of parentheses

-2r^2-10r-8=0

a = -2; b = -10; c = -8;
Δ = b2-4ac
Δ = -102-4·(-2)·(-8)
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-6}{2*-2}=\frac{4}{-4}
=-1
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+6}{2*-2}=\frac{16}{-4}
=-4
$