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**Identity****Member**- Registered: 2007-04-18
- Posts: 934

How about a marathon dedicated to any and all non-calculus topics?

**Rules:**

1. Calculus (limits, derivatives, integration), as well as other absurdly advanced topics (differential geometry, topology etc.) is forbidden. If that's your style you'll have to find another way.

2. Provide working for your solution

3. Post your own problem right after you have solved the previous one.

I'll get started,

*Find all roots of x:*

*Last edited by Identity (2007-09-04 02:09:49)*

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**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 21,298

Let x²-9x=y.

The equation becomes y²-7y+12=0

y=[7± √ (49-48)]/2= (7+1)/2or (7-1)/2=4 or 3.

Putting y=4,

x²-9x=4 or x²-9x-4=0.

x=[9± √(81+16)]/2= (9+ √97)/2 or (9- √97)/2.

Putting y=3,

x²-9x=3or x²-9x-3=0.

x=[9± √(81+12)]/2= (9+√93)/2 or (9-√93)/2.

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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