Solve the Floor Value of x in $x^2+1=2x$

  • Topic:
  • Thread starter Thread starter solakis1
  • Start date Start date
  • Tags Tags
    Value
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
3 replies · 2K views
solakis1
Messages
407
Reaction score
0
Solve the following equation

[$x^2+1$]=[2x] ,where [x] is the floor value of x
 
Mathematics news on Phys.org
I'm getting only $x=1$ as the answer.
Here is my approach please do tell me If I'm wrong.
we know that $x-1 \le [x] \lt x$ so
$x^2 \le [x^2+1] \lt x^2 + 1 $ and
$2x-1 \le [2x] \lt 2x$
so the upper limits and lower limits must be equal
$x^2 - 2x + 1 = 0$ $\implies$ $x=1$
 
DaalChawal said:
I'm getting only $x=1$ as the answer.
Here is my approach please do tell me If I'm wrong.
we know that $x-1 \le [x] \lt x$ so
$x^2 \le [x^2+1] \lt x^2 + 1 $ and
$2x-1 \le [2x] \lt 2x$
so the upper limits and lower limits must be equal
$x^2 - 2x + 1 = 0$ $\implies$ $x=1$
DaalChawal said:
so the upper limits and lower limits must be equal
Where do you base that assumption
I mean which axiom,definition ,theorem supports that assumption

The answer to the problem is : $x\in$[1/2,$\sqrt 2$)U[3/2,$\sqrt 3$)
Here we have that whole intervals is the answer