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Question 241709: solve (x+13)(x-15)(x+9)>0
a. solution set is.....
b. solution is all real numbers
c. there is no solution
Answer by College Student(505)   (Show Source):
You can put this solution on YOUR website! Since any number multiplied by zero equals zero ...AND... the inequality says the multiplication of these three terms is greater than zero... none of these terms can equal to zero. So, we will look for a solution set that avoids the multiplication by zero. Does that make sense? I know I used the word zero many times, if it confused you, please re-read it until it makes sense.
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Let x+13>0 ...same as... x>-13
Let x-15>0 ...same as... x>15
Let x+9>0 ...same as... x>-9
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The correct answer is: "a. solution set is..." {x>-13, and x>15, and x>-9}
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The answer cannot be "b. solution is all real numbers" because real numbers include all negative numbers as well as all positive numbers. We have already determined that the inequality is restricted to having all terms be greater than zero.
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The answer cannot be "c. there is no solution" because we were able to identify a valid set of answers.
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Hope this helped! :)
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