173=5.8875d2-1.57d

Solution for 173=5.8875d2-1.57d equation:

173=5.8875d^2-1.57d

We move all terms to the left:

173-(5.8875d^2-1.57d)=0

We get rid of parentheses

-5.8875d^2+1.57d+173=0

a = -5.8875; b = 1.57; c = +173;
Δ = b2-4ac
Δ = 1.572-4·(-5.8875)·173
Δ = 4076.6149
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$d_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1.57)-\sqrt{4076.6149}}{2*-5.8875}=\frac{-1.57-\sqrt{4076.6149}}{-11.775}
$
$d_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1.57)+\sqrt{4076.6149}}{2*-5.8875}=\frac{-1.57+\sqrt{4076.6149}}{-11.775}
$