Solving Equations that are Quadratic in Form

Some of these use u-substitution and some have extraneous roots (solutions). It's especially important to always check any solutions in the ORIGINAL equation as you may get an extraneous root (solution) which means it is not a solution. 

Solving an Equation that is Quadratic in Form 1

http://www.youtube.com/watch?v=9VDI66n13hk

Solving an Equation that is Quadratic in Form 2

http://www.youtube.com/watch?v=2N0tgulqC3s

Solving an Equation that is Quadratic in Form 3

http://www.youtube.com/watch?v=skrJkhIm78Q

Solving an Equation that is Quadratic in Form 4

http://www.youtube.com/watch?v=RRLgMycB6Xg