My Math Forum promise last one for today, -3+x/3 >= x/5-1

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September 22nd, 2016, 02:26 PM   #1
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promise last one for today, -3+x/3 >= x/5-1

-3+x/3 >= x/5-1

so I thought I would get 5x/15 -3x/15 =2x/15 >= 2

Yet besides that I am getting them all wrong, I don't think this is right because how would I get rid of the 2x/15?
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September 22nd, 2016, 02:43 PM   #2
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Quote:
 -3+x/3 >= x/5-1
multiply every term by 15 ...

$-45 + 5x \ge 3x - 15$

finish ...

September 23rd, 2016, 02:02 PM   #3
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Quote:
 Originally Posted by GIjoefan1976 -3+x/3 >= x/5-1 so I thought I would get 5x/15 -3x/15 =2x/15 >= 2 Yet besides that I am getting them all wrong, I don't think this is right because how would I get rid of the 2x/15?
$\displaystyle \frac{2x}{15}\ge 2\Rightarrow 2x\ge 30\Rightarrow x \ge 15$. I presume the problem was to get an inequality in x.

 October 24th, 2016, 01:12 AM #4 Member   Joined: Sep 2016 From: India Posts: 88 Thanks: 30 $-3+\dfrac{x}{3}\geq\dfrac{x}{5}-1$ Multiply each side by $15$ $\implies-45+5x\geq3x-15$ Separate the like terms, $\implies 5x-3x\geq45-15$ $\implies 2x\geq30$ $\implies x\geq15$ Last edited by deesuwalka; October 24th, 2016 at 01:18 AM.

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