301,44=3,14*r*(r+10)

Solution for 301,44=3,14*r*(r+10) equation:

301.44=3.14r(r+10)

We move all terms to the left:

301.44-(3.14r(r+10))=0


We calculate terms in parentheses: -(3.14r(r+10)), so:

3.14r(r+10)

We multiply parentheses

3r^2+30r

Back to the equation:

-(3r^2+30r)


We get rid of parentheses

-3r^2-30r+301.44=0

a = -3; b = -30; c = +301.44;
Δ = b2-4ac
Δ = -302-4·(-3)·301.44
Δ = 4517.28
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{-(-30)-\sqrt{4517.28}}{2*-3}=\frac{30-\sqrt{4517.28}}{-6}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-30)+\sqrt{4517.28}}{2*-3}=\frac{30+\sqrt{4517.28}}{-6}
$