3.5x^2+3x-7.875=0

Solution for 3.5x^2+3x-7.875=0 equation:

3.5x^2+3x-7.875=0

a = 3.5; b = 3; c = -7.875;
Δ = b2-4ac
Δ = 32-4·3.5·(-7.875)
Δ = 119.25
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{-(3)-\sqrt{119.25}}{2*3.5}=\frac{-3-\sqrt{119.25}}{7}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+\sqrt{119.25}}{2*3.5}=\frac{-3+\sqrt{119.25}}{7}
$