2.1x^2-840=0

Solution for 2.1x^2-840=0 equation:

2.1x^2-840=0

a = 2.1; b = 0; c = -840;
Δ = b2-4ac
Δ = 02-4·2.1·(-840)
Δ = 7056
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7056}=84$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-84}{2*2.1}=\frac{-84}{4.2}
=-20
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+84}{2*2.1}=\frac{84}{4.2}
=20
$