Sorry if this is in the wrong section. I wasn't sure where it went!

If you have an equation:

Which has roots

And you want an equation that has roots

How would you go about this by substitution? Because if i do

Im going to get alpha in terms of beta and u...and if i sub this into the equation im going to still have beta :S...

I know you can do it via sum of roots = -b/a etc but im told in this example to use substitution -,-.

Thanks.