105=-12n(-5n)

Solution for 105=-12n(-5n) equation:

105=-12n(-5n)

We move all terms to the left:

105-(-12n(-5n))=0


We calculate terms in parentheses: -(-12n(-5n)), so:

-12n(-5n)

We multiply parentheses

60n^2

Back to the equation:

-(60n^2)


a = -60; b = 0; c = +105;
Δ = b2-4ac
Δ = 02-4·(-60)·105
Δ = 25200
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{25200}=\sqrt{3600*7}=\sqrt{3600}*\sqrt{7}=60\sqrt{7}$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-60\sqrt{7}}{2*-60}=\frac{0-60\sqrt{7}}{-120}
=-\frac{60\sqrt{7}}{-120}
=-\frac{\sqrt{7}}{-2}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+60\sqrt{7}}{2*-60}=\frac{0+60\sqrt{7}}{-120}
=\frac{60\sqrt{7}}{-120}
=\frac{\sqrt{7}}{-2}
$