Thread: Difficult algebra..

How can I isolate y? y>0

55(1-y^20) = (1 - y^10)[30 + 60y^10 + 90y^20]

I'm having a really tough time. I get to:
0 = -3y^30 + 2.83 y^20 + y^10 - 0.83

I have no idea how to solve this kind of equation. Help?
(I realize I could replace y^10 = x, say, and get a third degree polynomial, but I'm not in the measure of solving such an equation ...)

Originally Posted by Volcanicrain

How can I isolate y? y>0

55(1-y^20) = (1 - y^10)[30 + 60y^10 + 90y^20]

I'm having a really tough time. I get to:
0 = -3y^30 + 2.83 y^20 + y^10 - 0.83

I have no idea how to solve this kind of equation. Help?
(I realize I could replace y^10 = x, say, and get a third degree polynomial, but I'm not in the measure of solving such an equation ...)

Notice that you can factor the left side as the difference of two squares:



Do you see how you can cancel now?

Wow that's amazing! Thanks a million You really helped me out!

You can now write:



If you let you can write this as:




The let

So now this takes the form of a quadratic.



Where is can be treated as a constant. You should be able to isolate y by factoring or using the quadratic formula.

I was able to, thanks a lot I got the right answer for my problem!!
You're a godsend!
Could I directly substitute k = y^10 ?

Originally Posted by Volcanicrain

I was able to, thanks a lot I got the right answer for my problem!!
You're a godsend!
Could I directly substitute k = y^10 ?

Absolutely