(-3-x)x=-400

Solution for (-3-x)x=-400 equation:

(-3-x)x=-400

We move all terms to the left:

(-3-x)x-(-400)=0

We add all the numbers together, and all the variables

(-1x-3)x-(-400)=0

We add all the numbers together, and all the variables

(-1x-3)x+400=0

We multiply parentheses

-1x^2-3x+400=0

a = -1; b = -3; c = +400;
Δ = b2-4ac
Δ = -32-4·(-1)·400
Δ = 1609
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-3)-\sqrt{1609}}{2*-1}=\frac{3-\sqrt{1609}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-3)+\sqrt{1609}}{2*-1}=\frac{3+\sqrt{1609}}{-2}
$