15n^2+26n-21=0

Solution for 15n^2+26n-21=0 equation:

15n^2+26n-21=0

a = 15; b = 26; c = -21;
Δ = b2-4ac
Δ = 262-4·15·(-21)
Δ = 1936
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1936}=44$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(26)-44}{2*15}=\frac{-70}{30}
=-2+1/3
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(26)+44}{2*15}=\frac{18}{30}
=3/5
$