l^2-14l-196=0

Solution for l^2-14l-196=0 equation:

l^2-14l-196=0

a = 1; b = -14; c = -196;
Δ = b2-4ac
Δ = -142-4·1·(-196)
Δ = 980
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$l_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$l_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{980}=\sqrt{196*5}=\sqrt{196}*\sqrt{5}=14\sqrt{5}$
$l_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-14\sqrt{5}}{2*1}=\frac{14-14\sqrt{5}}{2}
$
$l_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+14\sqrt{5}}{2*1}=\frac{14+14\sqrt{5}}{2}
$