28y-y^2-187=0

Solution for 28y-y^2-187=0 equation:

28y-y^2-187=0

We add all the numbers together, and all the variables

-1y^2+28y-187=0

a = -1; b = 28; c = -187;
Δ = b2-4ac
Δ = 282-4·(-1)·(-187)
Δ = 36
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{36}=6$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-6}{2*-1}=\frac{-34}{-2}
=+17
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+6}{2*-1}=\frac{-22}{-2}
=+11
$