21x^2+21=-58x

Solution for 21x^2+21=-58x equation:

21x^2+21=-58x

We move all terms to the left:

21x^2+21-(-58x)=0

We get rid of parentheses

21x^2+58x+21=0

a = 21; b = 58; c = +21;
Δ = b2-4ac
Δ = 582-4·21·21
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(58)-40}{2*21}=\frac{-98}{42}
=-2+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(58)+40}{2*21}=\frac{-18}{42}
=-3/7
$