4x^2+80x+400=900

Solution for 4x^2+80x+400=900 equation:

4x^2+80x+400=900

We move all terms to the left:

4x^2+80x+400-(900)=0

We add all the numbers together, and all the variables

4x^2+80x-500=0

a = 4; b = 80; c = -500;
Δ = b2-4ac
Δ = 802-4·4·(-500)
Δ = 14400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{14400}=120$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(80)-120}{2*4}=\frac{-200}{8}
=-25
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(80)+120}{2*4}=\frac{40}{8}
=5
$