SOLUTION: Hi! My teacher told me that you change the sign for the inequality only if the negative number is on the left side (with the variable) when you are dividing or multiplying, is that

Algebra ->  Inequalities -> SOLUTION: Hi! My teacher told me that you change the sign for the inequality only if the negative number is on the left side (with the variable) when you are dividing or multiplying, is that      Log On


   

Question 525872: Hi! My teacher told me that you change the sign for the inequality only if the negative number is on the left side (with the variable) when you are dividing or multiplying, is that true? Then if you have a question like -3x>9 then the sign will be changed but if you have 3x>-9 then the sign will not be changed because the negative number is on the right. Please answer this question, I really don't get it, and on a test I didn't change the sign if the negative number was on the right. Please answer as soon as possible, I'm really scared and worried right now! Thank you for answering! :)
Found 2 solutions by scott8148, richwmiller:
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
not sure about left and right ...

but the "rule" is ___ multiplying or dividing by a negative value changes the direction of the inequality arrow

ex. ___ 9 < 18 ___ but dividing by -3 ___ -3 > -6

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
Your teacher is right and wrong.
in the negative left side example
-3x>9
you divide by -3 to get
x<-3 and you change the sign.
with the negative right side you divide by +3 and get
3x>-9
x>-3
You don't divide by -3 in the second problem so you wouldn't change the sign