5r^2+9r-20=-2

Solution for 5r^2+9r-20=-2 equation:

5r^2+9r-20=-2

We move all terms to the left:

5r^2+9r-20-(-2)=0

We add all the numbers together, and all the variables

5r^2+9r-18=0

a = 5; b = 9; c = -18;
Δ = b2-4ac
Δ = 92-4·5·(-18)
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-21}{2*5}=\frac{-30}{10}
=-3
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+21}{2*5}=\frac{12}{10}
=1+1/5
$