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July 30, 2015

July 30, 2015

Posted by **jase** on Friday, November 25, 2011 at 11:35pm.

the absolute value of x-2/3 is less than or equal to 4

- precalculus -
**Steve**, Saturday, November 26, 2011 at 12:01am|x - 2/3| <= 4

if x - 2/3 >= 0 then |x - 2/3| = x - 2/3

In that case,

x - 2/3 <= 4

x <= 14/3 and x >= 2/3 (remember x - 2/3 >= 0)

so, x is in [2/3 , 14/3]

if x - 2/3 >= 0 then |x - 2/3| = -(x - 2/3)

In that case,

2/3 - x <= 4

x >= -10/3

But x - 2/3 < 0 means x < 2/3

So,

x is in [-10/3 , 2/3)

So, finally, x is in [-10/3 , 2/3)U[2/3 , 14/3]

or, x is in [-10/3 , 14/3]

This makes sense. Think of the graph of |x|. It is a V shape. If |x| < k, then you want the part of the V below the line y=k.

In this case, the V is shifted 2/3 to the right, and we want the part of the V below the line y=4