Can you find roots of roots?

Algebra Level 2

x + 2 x + 2 x + 2 3 x = x \large \sqrt{x + 2\sqrt{x + 2 \sqrt{x + 2\sqrt{3x}}}} = x

Find the non zero root of the equation above.


The answer is 3.

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6 solutions

Rajdeep Dhingra
Oct 18, 2014

x + 2 x + 2 x + 2 3 x = x W e a l s o k n o w t h a t x = x 2 = x + ( x 1 ) x = x + ( x 1 ) x + ( x 1 ) x = x + ( x 1 ) x + ( x 1 ) x + ( x 1 ) x = x + ( x 1 ) x + ( x 1 ) x + ( x 1 ) x 2 N o w w e c o m p a r e t h i s w i t h a r e q u e s t i o n W e g e t 3 x = x 2 3 x = x 2 x = 3 A N S \sqrt { x\quad +\quad 2\sqrt { x\quad +\quad 2\sqrt { x\quad +\quad 2\sqrt { 3x } } } } =\quad x\\ We\quad also\quad know\quad that\quad \\ x\quad =\quad \sqrt { { x }^{ 2 } } \quad =\quad \sqrt { x\quad +\quad (x\quad -\quad 1)x } \\ =\sqrt { x\quad +\quad (x\quad -\quad 1)\sqrt { x\quad +\quad (x\quad -\quad 1)x } } \\ =\sqrt { x\quad +\quad (x\quad -\quad 1)\sqrt { x\quad +\quad (x\quad -\quad 1)\sqrt { x\quad +\quad (x\quad -\quad 1)x } } } \\ =\sqrt { x\quad +\quad (x\quad -\quad 1)\sqrt { x\quad +\quad (x\quad -\quad 1)\sqrt { x\quad +\quad (x\quad -\quad 1)\sqrt { { x }^{ 2 } } } } } \quad \\ Now\quad we\quad compare\quad this\quad with\quad are\quad question\\ We\quad get\quad \\ \sqrt { 3x } \quad =\quad \sqrt { { x }^{ 2 } } \\ 3x\quad =\quad { x }^{ 2 }\\ x\quad =\quad 3\quad \leftarrow ANS Quite Easily Done Quite Easily Done

Good question. Actually x = 0 x=0 is also a solution. The question has to be reworded. A tough question. I solved it numerically.

Chew-Seong Cheong - 6 years, 6 months ago

I thought it was Quantum Electro-Dynamics :P

Ahmed Hazem - 6 years ago
Sankalp Ranjan
Jun 8, 2015

Write 3x as x+2x. Now, if we assume this as an Infinite Loop, x+2x seems to be a result of x+2 root ( ...... ).

So this root ( .......... ) = x Therefore, root ( x + 2x ) = x, i.e. x^2 = 3x or, x = 3.

Istiak Reza
Jun 26, 2015

The last term 3x can be written as x+2x...now we can put the value of x, that is left side of the equation for 2(left side of the equation)....We notice that this can be repeated infinite times.....thus we can write ✓( x + 2×)=x Solving we get x=0,3....thus the non zero ans is 3

Ahmed Hazem
Jun 9, 2015

that was pure luck :P really i had no idea it would be 3

Anindya Maity
Nov 30, 2014

squaring both side we get x^2=3x but x not equal to zero so x=3

Aditya Tiwari
Nov 20, 2014

Why can't zero be the solution? Wasted one try in that ;)

I have made the Changes Thanks for noticing.

Rajdeep Dhingra - 6 years, 6 months ago

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