2440.36=r^2+2.4r^2

Solution for 2440.36=r^2+2.4r^2 equation:

2440.36=r^2+2.4r^2

We move all terms to the left:

2440.36-(r^2+2.4r^2)=0

We get rid of parentheses

-r^2-2.4r^2+2440.36=0

We add all the numbers together, and all the variables

-3.4r^2+2440.36=0

a = -3.4; b = 0; c = +2440.36;
Δ = b2-4ac
Δ = 02-4·(-3.4)·2440.36
Δ = 33188.896
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{-(0)-\sqrt{33188.896}}{2*-3.4}=\frac{0-\sqrt{33188.896}}{-6.8}
=-\frac{\sqrt{}}{-6.8}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{33188.896}}{2*-3.4}=\frac{0+\sqrt{33188.896}}{-6.8}
=\frac{\sqrt{}}{-6.8}
$