0.21x^2+2.84x-42.57=0

Solution for 0.21x^2+2.84x-42.57=0 equation:

0.21x^2+2.84x-42.57=0

a = 0.21; b = 2.84; c = -42.57;
Δ = b2-4ac
Δ = 2.842-4·0.21·(-42.57)
Δ = 43.8244
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{-(2.84)-\sqrt{43.8244}}{2*0.21}=\frac{-2.84-\sqrt{43.8244}}{0.42}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2.84)+\sqrt{43.8244}}{2*0.21}=\frac{-2.84+\sqrt{43.8244}}{0.42}
$