x^2+-8.4x+200=0

Solution for x^2+-8.4x+200=0 equation:

x^2+-8.4x+200=0

We add all the numbers together, and all the variables

x^2-8.4x=0

a = 1; b = -8.4; c = 0;
Δ = b2-4ac
Δ = -8.42-4·1·0
Δ = 70.56
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{-(-8.4)-\sqrt{70.56}}{2*1}=\frac{8.4-\sqrt{70.56}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8.4)+\sqrt{70.56}}{2*1}=\frac{8.4+\sqrt{70.56}}{2}
$