Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

## #1 2007-09-05 00:07:45

Identity
Power Member

Offline

### Miscellaneous Math Marathon

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 (2007-09-05 00:09:49)

## #2 2007-10-01 00:30:37

ganesh
Moderator

Offline

### Re: Miscellaneous Math Marathon

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.

Character is who you are when no one is looking.