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inequality 3

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inequality 3

by Gurpinder » Wed Sep 01, 2010 12:11 pm
|x+5|≥2

x≥-3
x≥-7

so wouldn't you say that x is ≥ -7?
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by Brian@VeritasPrep » Wed Sep 01, 2010 1:44 pm
Hey Gurpinder,

When you're looking at those inequalities with absolute values, it's usually worth the extra step to be pretty methodical.

If |x+5| > 2 (excuse me for not using the "or equal to"...way too much of a hassle to search for extra symbols!)

Then either

x + 5 > 2

or

x + 5 < -2

So, subtracting 5 in each to isolate x, either:

x > -3

or

x < -7


If you end up with an "or" inequality like you did that seems redundant (x > -7 OR x > -3, which doesn't make sense), check to see if you've either forgotten to switch the direction of the inequality or the sign of a negative/positive shift, as that's probably the culprit...
Last edited by Brian@VeritasPrep on Wed Sep 01, 2010 1:50 pm, edited 1 time in total.
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by Gurpinder » Wed Sep 01, 2010 1:47 pm
Thanks Brian

I actually realized my error!

x + 5 > +2

or

x + 5 < -2

I wasn't flipping the sign when taking the 2 to be negative.
"Do not confuse motion and progress. A rocking horse keeps moving but does not make any progress."
- Alfred A. Montapert, Philosopher.
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