56r^2-17r-3=0

Solution for 56r^2-17r-3=0 equation:

56r^2-17r-3=0

a = 56; b = -17; c = -3;
Δ = b2-4ac
Δ = -172-4·56·(-3)
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-17)-31}{2*56}=\frac{-14}{112}
=-1/8
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-17)+31}{2*56}=\frac{48}{112}
=3/7
$