5n^2-3n-15=25

Solution for 5n^2-3n-15=25 equation:

5n^2-3n-15=25

We move all terms to the left:

5n^2-3n-15-(25)=0

We add all the numbers together, and all the variables

5n^2-3n-40=0

a = 5; b = -3; c = -40;
Δ = b2-4ac
Δ = -32-4·5·(-40)
Δ = 809
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-\sqrt{809}}{2*5}=\frac{3-\sqrt{809}}{10}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+\sqrt{809}}{2*5}=\frac{3+\sqrt{809}}{10}
$