p+2p-p^2=0.4

Solution for p+2p-p^2=0.4 equation:

p+2p-p^2=0.4

We move all terms to the left:

p+2p-p^2-(0.4)=0

We add all the numbers together, and all the variables

-1p^2+3p-0.4=0

a = -1; b = 3; c = -0.4;
Δ = b2-4ac
Δ = 32-4·(-1)·(-0.4)
Δ = 7.4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$p_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$p_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$p_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-\sqrt{7.4}}{2*-1}=\frac{-3-\sqrt{7.4}}{-2}
$
$p_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+\sqrt{7.4}}{2*-1}=\frac{-3+\sqrt{7.4}}{-2}
$