3.5x^2-56x-126=0

Solution for 3.5x^2-56x-126=0 equation:

3.5x^2-56x-126=0

a = 3.5; b = -56; c = -126;
Δ = b2-4ac
Δ = -562-4·3.5·(-126)
Δ = 4900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4900}=70$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-56)-70}{2*3.5}=\frac{-14}{7}
=-2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-56)+70}{2*3.5}=\frac{126}{7}
=18
$