b^2=-4b+73

Solution for b^2=-4b+73 equation:

b^2=-4b+73

We move all terms to the left:

b^2-(-4b+73)=0

We get rid of parentheses

b^2+4b-73=0

a = 1; b = 4; c = -73;
Δ = b2-4ac
Δ = 42-4·1·(-73)
Δ = 308
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{308}=\sqrt{4*77}=\sqrt{4}*\sqrt{77}=2\sqrt{77}$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-2\sqrt{77}}{2*1}=\frac{-4-2\sqrt{77}}{2}
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+2\sqrt{77}}{2*1}=\frac{-4+2\sqrt{77}}{2}
$