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# Inequalities

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1. when you have x<3 then you have -x<-3 do you have to flip that < sign or do you not?
2. (Original post by thefatone)
when you have x<3 then you have -x<-3 do you have to flip that < sign or do you not?
Of course you do. Example with x=1:

1 < 3

-1 < -3? (not true)

-1 > -3. (true)
3. (Original post by Zacken)
Of course you do. Example with x=1:

1 < 3

-1 < -3? (not true)

-1 > -3. (true)
so if i have -x>-3 to solve for x i would then have to say x<3??
4. With algebra both sides of the equation are changed but with Inequalities both sides AND the sign is changed.
5. (Original post by thefatone)
so if i have -x>-3 to solve for x i would then have to say x<3??
Yes. Example:

-2 > -3

2 < 3
6. But if x was 4... Then we get
-4<-3 which is true

Posted from TSR Mobile
7. If you multiply by a negative, you flip the sign.
8. (Original post by Zacken)
Yes. Example:

-2 > -3

2 < 3
right.....

thanks so much, you're so useful i reckon you could be an awesome teacher
9. If you have -x<-3 then add x to both sides. We get -x+x<-3+x, i.e. 0<-3+x. Now add 3 to both sides. 0+3<-3+x+3, i.e. 3<x.

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