0=5n^2+25n-70

Solution for 0=5n^2+25n-70 equation:

0=5n^2+25n-70

We move all terms to the left:

0-(5n^2+25n-70)=0

We add all the numbers together, and all the variables

-(5n^2+25n-70)=0

We get rid of parentheses

-5n^2-25n+70=0

a = -5; b = -25; c = +70;
Δ = b2-4ac
Δ = -252-4·(-5)·70
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-25)-45}{2*-5}=\frac{-20}{-10}
=+2
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25)+45}{2*-5}=\frac{70}{-10}
=-7
$