If √x+√x+√x+√x+⋯=9, find x.
I know that if this equation were switched around, where the x is 9 and 9 is x instead, we'd solve it like this:
√9+√9+√9+√9+⋯=xx2=9+√9+√9+√9+⋯x2=9+xx2−x−9=0x=1+√372
I think I should be applying the same logic, but it's kind of difficult because of the x and it's making me confused. Could anyone help?
Your instinct is correct!
Call that whose expression on the left side of the equal sign "expression" so you have
[expression] = 9
Square both sides -- you'll get:
x + [expression] = 81
Since [expression] = 9 -- by substituting '9' for [expression] -- you'll now have:
x + 9 = 81
Therefore, x = 72