Posted by Brad Paul on October 06, 2002 at 19:18:51:
In Reply to: PLEASE HELP I NEED THIS NOW! posted by jen on October 06, 2002 at 15:39:34:
: can u please solve this c/3 + 2 is less than equal to c/5 + 1 whats the answer!!?? its drivin me nuts
Jen,
Please excuse the other response. There have been some fools
responding with other peoples names.
I imagine your question is solve for c. Let me rewrite the equation:
c/3+2<=c/5+1
This problem is almost identical to solving for c with an equal
sign. The only difference is when we multiply or divide by a negative
number we need to flip the "<" or ">" symbol. Let me give a simple
numerical example. We know the following is true:
-3<4 <- true
Now lets multiply by -1 on each side and see what we get.
3<-4 <- not true
This is no longer true. To make it true we must flip the "<" to a ">"
which will give us the correct result:
3>-4 <- true
Now when we work with an equation that has variables in it we must be
very careful to flip the "<" or ">" when we multiply or divide by a
negative quantity.
Now let's do you question:
Move the terms with the c to one side and the free numbers to the other side:
c/3-c/5<=1-2
(5 c)/15- (3 c)/15 <= -1
(2 c)/15 <= -1
(2 c) <= -15
c <= -15/2
In this case we never had to worry about the flipping of the "<" or ">" sign.