Solve an Equation in Quadratic Form Using Substitution and Factoring (Square Root)

[brusilshelby]

Nice video, I always wanted to know how to solve these equations, thank you!

[MrPaulc]

I tend to do these a bit differently, so it's helpful to see another way. Thank you.
Rearrange: m + 20 = 9*sqrt(m)
Square: m^2 + 40m + 400 = 81m
Rearrange: m^2 - 41m + 400 = 0 for a quadratic.
(41+or-sqrt(1681 - 4*1*400))/2
41+or-sqrt(81))/2
sqrt(81) = 9, so solutions of 25 and 16.
I did the same with the other equation