121/5r=2r+1

Solution for 121/5r=2r+1 equation:

121/5r=2r+1

We move all terms to the left:

121/5r-(2r+1)=0


Domain of the equation: 5r!=0

r!=0/5

r!=0

r∈R


We get rid of parentheses

121/5r-2r-1=0

We multiply all the terms by the denominator


-2r*5r-1*5r+121=0

Wy multiply elements

-10r^2-5r+121=0

a = -10; b = -5; c = +121;
Δ = b2-4ac
Δ = -52-4·(-10)·121
Δ = 4865
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{-(-5)-\sqrt{4865}}{2*-10}=\frac{5-\sqrt{4865}}{-20}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{4865}}{2*-10}=\frac{5+\sqrt{4865}}{-20}
$