(136*3.14)^2=r^2-4r

Solution for (136*3.14)^2=r^2-4r equation:

(136*3.14)^2=r^2-4r

We move all terms to the left:

(136*3.14)^2-(r^2-4r)=0

We add all the numbers together, and all the variables

-(r^2-4r)+(427.04)^2=0

We add all the numbers together, and all the variables

-(r^2-4r)+182363.1616=0

We get rid of parentheses

-r^2+4r+182363.1616=0

We add all the numbers together, and all the variables

-1r^2+4r+182363.1616=0

a = -1; b = 4; c = +182363.1616;
Δ = b2-4ac
Δ = 42-4·(-1)·182363.1616
Δ = 729468.6464
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-\sqrt{729468.6464}}{2*-1}=\frac{-4-\sqrt{729468.6464}}{-2}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+\sqrt{729468.6464}}{2*-1}=\frac{-4+\sqrt{729468.6464}}{-2}
$