1400000=-4p^2+8000p

Solution for 1400000=-4p^2+8000p equation:

1400000=-4p^2+8000p

We move all terms to the left:

1400000-(-4p^2+8000p)=0

We get rid of parentheses

4p^2-8000p+1400000=0

a = 4; b = -8000; c = +1400000;
Δ = b2-4ac
Δ = -80002-4·4·1400000
Δ = 41600000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$p_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$p_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{41600000}=\sqrt{640000*65}=\sqrt{640000}*\sqrt{65}=800\sqrt{65}$
$p_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8000)-800\sqrt{65}}{2*4}=\frac{8000-800\sqrt{65}}{8}
$
$p_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8000)+800\sqrt{65}}{2*4}=\frac{8000+800\sqrt{65}}{8}
$