21n^2-61n+28=0

Solution for 21n^2-61n+28=0 equation:

21n^2-61n+28=0

a = 21; b = -61; c = +28;
Δ = b2-4ac
Δ = -612-4·21·28
Δ = 1369
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1369}=37$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-61)-37}{2*21}=\frac{24}{42}
=4/7
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-61)+37}{2*21}=\frac{98}{42}
=2+1/3
$