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usaboy94
Aug 13, 2009, 06:38 PM
-5x+-3>2(3+x)
I know the answer is x<-9/7, but I don't know how to get that answer. I need to get a step by step.

morgaine300
Aug 13, 2009, 08:30 PM
Would you know how to solve this if it weren't an inequality? Because the process is the same with one exception.

You want to start by distributing your 2 on the right side.

-5x - 3\, >\, 6 + 2x
(May as well write the "+ -3" as just -3 since that's what it means.)

Then you want to get like terms together. You can do this in either order. Add 3 to both sides:

-5x - 3 + 3\,>\, 6 + 2x + 3

-5x \,>\, 9 + 2x

Then subtract 2x from both sides

-5x - 2x\,>\, 9 + 2x - 2x

-7x\, >\, 9

You can now divide out the -7.

\frac{-7x}{-7}\, >\, \frac{9}{-7}

Here's where the difference comes in. When you divide or multiple a negative in an inequality, it turns the sign around. The > is going to become a <.

x\, <\,-\frac{9}{7}

usaboy94
Aug 14, 2009, 12:29 PM
Would you know how to solve this if it weren't an inequality? Because the process is the same with one exception.

You want to start by distributing your 2 on the right side.

-5x - 3\, >\, 6 + 2x
(May as well write the "+ -3" as just -3 since that's what it means.)

Then you want to get like terms together. You can do this in either order. Add 3 to both sides:

-5x - 3 + 3\,>\, 6 + 2x + 3

-5x \,>\, 9 + 2x

Then subtract 2x from both sides

-5x - 2x\,>\, 9 + 2x - 2x

-7x\, >\, 9

You can now divide out the -7.

\frac{-7x}{-7}\, >\, \frac{9}{-7}

Here's where the difference comes in. When you divide or multiple a negative in an inequality, it turns the sign around. The > is going to become a <.

x\, <\,-\frac{9}{7}


Thanks

morgaine300
Aug 14, 2009, 07:33 PM
You're welcome. :-)