-3n(n-5)=(-9)

Solution for -3n(n-5)=(-9) equation:

-3n(n-5)=(-9)

We move all terms to the left:

-3n(n-5)-((-9))=0

We add all the numbers together, and all the variables

-3n(n-5)+9=0

We multiply parentheses

-3n^2+15n+9=0

a = -3; b = 15; c = +9;
Δ = b2-4ac
Δ = 152-4·(-3)·9
Δ = 333
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:

$\sqrt{\Delta}=\sqrt{333}=\sqrt{9*37}=\sqrt{9}*\sqrt{37}=3\sqrt{37}$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-3\sqrt{37}}{2*-3}=\frac{-15-3\sqrt{37}}{-6}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+3\sqrt{37}}{2*-3}=\frac{-15+3\sqrt{37}}{-6}
$