# Sign Charts

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• February 20th 2009, 03:31 PM
AlgebraicallyChallenged
Sign Charts
Dear Forum I have tried to figure this one out several times but I am still having no luck if anyone can help please let me know, it would be greatly appreciated.
Solve x^2 + 11x + 18 > 0 using the Critical Value (Sign Chart) method.

Thanks -AC-
• February 20th 2009, 03:42 PM
skeeter
find the x-values where $x^2 + 11x + 18 = 0$

plot these two x-values on a number line ... the two plotted solutions break up the number line into three intervals.

pick a single value in each interval and "test" it to see if that value makes the original inequality true or false ... if true, then all values in that interval make the inequality true and are part of the solution set.

if the chosen value from the interval makes the original inequality false, then exclude that interval of values from the solution set.
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