39x^2+2.5x-1.56=0

Solution for 39x^2+2.5x-1.56=0 equation:

39x^2+2.5x-1.56=0

a = 39; b = 2.5; c = -1.56;
Δ = b2-4ac
Δ = 2.52-4·39·(-1.56)
Δ = 249.61
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{-(2.5)-\sqrt{249.61}}{2*39}=\frac{-2.5-\sqrt{249.61}}{78}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(2.5)+\sqrt{249.61}}{2*39}=\frac{-2.5+\sqrt{249.61}}{78}
$