14400=960x-7x^2

Solution for 14400=960x-7x^2 equation:

14400=960x-7x^2

We move all terms to the left:

14400-(960x-7x^2)=0

We get rid of parentheses

7x^2-960x+14400=0

a = 7; b = -960; c = +14400;
Δ = b2-4ac
Δ = -9602-4·7·14400
Δ = 518400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{518400}=720$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-960)-720}{2*7}=\frac{240}{14}
=17+1/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-960)+720}{2*7}=\frac{1680}{14}
=120
$