x^2-2.5x-12=0

Solution for x^2-2.5x-12=0 equation:

x^2-2.5x-12=0

a = 1; b = -2.5; c = -12;
Δ = b2-4ac
Δ = -2.52-4·1·(-12)
Δ = 54.25
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{-(-2.5)-\sqrt{54.25}}{2*1}=\frac{2.5-\sqrt{54.25}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2.5)+\sqrt{54.25}}{2*1}=\frac{2.5+\sqrt{54.25}}{2}
$