High School Can You Solve This Week's Math Challenge Equation?

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    2016
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This week's Problem of the Week (POTW) presents the equation $$x^3=4+\left\lfloor{x}\right\rfloor$$. The correct solution was provided by user IanCg, demonstrating the effective application of mathematical concepts involving floor functions and cubic equations. Participants are encouraged to refer to the guidelines on the Math Help Boards for proper submission procedures and to engage with the community for further discussions.

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Here is this week's POTW:
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Solve the equation $$x^3=4+\left\lfloor{x}\right\rfloor$$.

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Remember to read the http://www.mathhelpboards.com/showthread.php?772-Problem-of-the-Week-%28POTW%29-Procedure-and-Guidelines to find out how to http://www.mathhelpboards.com/forms.php?do=form&fid=2!
 
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Congratulations to IanCg for his correct solution, which you can find below::)

For $x < 0,\, x^3-4 < x-1 \leqslant\left\lfloor{x}\right\rfloor$ so there are no solutions in this range
For$ x >2,\, x^3 - 4 > x \geqslant\left\lfloor{x}\right\rfloor$ so no solutions in this range
for $0\le x < 1,\, x^3-4$ is negative and $\left\lfloor{x}\right\rfloor = 0$ so no solutions

View attachment 6303

The only range for a solution is $1\le x<2$ in this case $\left\lfloor{x}\right\rfloor = 1$
So the equation becomes $x^3 - 4 = 1 $
So the solution is $x = \left\lfloor{\sqrt[3]{5}}\right\rfloor$
 

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