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July 12th, 2019, 08:57 PM   #1
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A grade three equation

Hello all,

Solve the equation $\displaystyle x^3-\{x \}^2+i[x]-1=0$ where $\displaystyle i^2=-1$.

All the best,

Integrator
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July 13th, 2019, 02:56 AM   #2
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What do $\{x\}$ and $[x]$ mean in your equation?
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July 13th, 2019, 07:49 AM   #3
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Math Focus: Yet to find out.
That’s some smart 3rd graders
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July 13th, 2019, 01:11 PM   #4
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Originally Posted by Joppy View Post
That’s some smart 3rd graders
I assumed they meant 3rd-order.

I can give you the engineering solution (attached).
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File Type: png 3rdOrder.png (16.3 KB, 1 views)
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July 13th, 2019, 10:03 PM   #5
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What do $\{x\}$ and $[x]$ mean in your equation?
Hello,

$\displaystyle x=[x]+\{x\}$.Par exemple $\displaystyle [-3.7]=-4$ and $\displaystyle \{-3.7\}=0.3$.

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Integrator

Last edited by Integrator; July 13th, 2019 at 10:11 PM.
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July 13th, 2019, 10:10 PM   #6
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I assumed they meant 3rd-order.

I can give you the engineering solution (attached).
Hello,

How did You calculate?Thank you very much!

All the best,

Integrator
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July 14th, 2019, 07:40 AM   #7
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Hello,

[MATH]$\displaystyle \{-3.7\}=0.3$.

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Integrator
did you mean 0.7?
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July 14th, 2019, 08:01 AM   #8
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did you mean 0.7?
Hello,

No!If $\displaystyle [-3.7]=-4$ , then $\displaystyle \{-3.7\}=0.3$.

Al the best,

Integrator
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July 14th, 2019, 09:03 AM   #9
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How did You calculate?
I didn't; I asked MATLAB to do it for me. Of course, that was before I knew what [x] and {x} meant in your equation.
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July 14th, 2019, 10:06 AM   #10
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What definitions apply if $x$ isn't real? If $x$ has to be real, $0 < x < 1$, in order that $[x]= 0$, but there are no values of $x$ in that range that satisfy the equation.
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