We have the equation:
[tex]-y^2-36=-12y[/tex]
let's write in the standard form to identify the values of the constants:
[tex]y^2-12y+36=0[/tex]
from this we notice that a=1, b=-12 and c=36. Plugging this values into the discriminant we have:
[tex](-12)^2-4(1)(36)=144-144=0[/tex]
Since the discriminant is equal to zero that means that the equation has only one solution of multiplicity 2.
Let's find the solution with the general formula; plugging the values of a, b and c we have:
[tex]\begin{gathered} y=\frac{-(-12)\pm\sqrt[]{(-12)-4(1)(36)}}{2(1)} \\ =\frac{12\pm\sqrt[]{0}}{2} \\ =\frac{12}{2} \\ =6 \end{gathered}[/tex]
Therefore the solution of the equation is 6.
