21x^2-144x-192=0

Solution for 21x^2-144x-192=0 equation:

21x^2-144x-192=0

a = 21; b = -144; c = -192;
Δ = b2-4ac
Δ = -1442-4·21·(-192)
Δ = 36864
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36864}=192$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-144)-192}{2*21}=\frac{-48}{42}
=-1+1/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-144)+192}{2*21}=\frac{336}{42}
=8
$