Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °
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#2 2008-01-26 08:00:31
- mathsyperson
- Moderator
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Re: x∈ [-5,4]
x² ∈ [0,25]
1/x ∈ (-∞,-1/5] U [1/4,∞)
Why did the vector cross the road?
It wanted to be normal.