Ix+3I<14
that means x+3 < 14 or -(x+3) < 14 the first relation can be written as x +3 -3 < 14 -3 (add -3 to both sides) simplify (3-3 is 0) and 14-3 is 11 : x < 11 for the second relation, distribute the - sign: -(x+3) means -1*(x+3) multiply -1 times each term in the parens: -x -3 so you now have -x -3 < 14 if you leave it -x we will eventually have to "flip" the < sign. It is safer to always add and if you have to divide by POSITIVE numbers. so add +x to both sides +x -x -3 < 14+x x-x is 0, so we get -3 < 14+x now add -14 to both sides -3-14 < 14+x-14 which simplifies to -17 < x the answer is -17 < x and x < 11 you can write this as -17 < x < 11
thank you very much
Here is a video if you want to see these worked out http://www.khanacademy.org/math/algebra/linear_inequalities/compound_absolute_value_inequali/v/absolute-value-inequalities
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