x x x x x x x ⋯ = ?
In other words, what happens if we keep doing this forever? (Note that x ⩾ 0 .)
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Nice job @Liviu Florescu . That's the same general train of thought I had when making the problem. :)
y = x x x x x x x x x x x . . .
y = x y
Squring both sides.
y 2 = x y
y = x
x = x x x x x x x x x x x . . .
This solution is incomplete for two reasons: First you do not show that the nested root actually converges, and secondly you need to examine the possibility that y = 0 but x = 0 .
Interesting approach. One I had not thought of. Very clever, though.
n = x x x x x x x ⋯
n 2 = x x x x x x x x ⋯
n 2 = x n
n 2 − x n = 0
n ( n − x ) = 0
∴ n = 0 , n − x = 0
n = 0 , x
When n is 0 :
0 = x x x x x x x ⋯
0 2 = x x x x x x x x ⋯
x = 0
x ≥ 0 ∴ x = 0
Since x = 0 the only other solution is:
x = x x x x x x x ⋯
Cool solution, @Jack Rawlin. I hadn't thought of it that way, but it's very clear and logical.
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Thanks, I do try to make my solutions as logical as possible.
How do we know that x != 0 from the inequality/work that you did? Thanks. @Jack Rawlin
Notice this example: 4 1 6 = 4 ⋅ 4 1 6 = 4 . So, as we add more roots, we divide by a higher power of 2. We can look at this as a geometric series: ∑ 1 ∞ 2 n 1 . And we can find the convergence of a geometric series with: 1 − ∣ r ∣ a . If we do that, we get 1 − 0 . 5 0 . 5 = 1 . So, lim x → ∞ x x x x x x x x x x x . . . = x 1 .
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for me, the expression is equivalent to x 2 1 × x 4 1 × x 8 1 × x 1 6 1 . . . . which is equivalent to x 2 1 + 4 1 + 8 1 + 1 6 1 . . . and we know 2 1 + 4 1 + 8 1 + 1 6 1 . . . converges to 1 , therefore the main expresion coverges to x 1 which is x