Absolute Value Inequalities (1 Viewer)

[ultimatecricker]

Hey guys,

For the question [x + 2] > 3x + 7 can you tell me what answers you got so i can check if my answer is correct. The [ ] denote the absolute sign.

Using my tutors method, x + 2 < -3x -7 and x + 2 > 3x + 7. So the final solution is x < -5/2. Is this right?

 

[RealiseNothing]

There are two cases:



and



This is because the absolute value is defined as:

and

 

[RivalryofTroll]

Hey guys,

For the question [x + 2] > 3x + 7 can you tell me what answers you got so i can check if my answer is correct. The [ ] denote the absolute sign.

Using my tutors method, x + 2 < -3x -7 and x + 2 > 3x + 7. So the final solution is x < -5/2. Is this right?

Just use www.wolframalpha.com next time if you need to check answers.
Unless, you need full solutions.

 

[Marc26]

Wouldn't the answer be:

Positive method:
x+2 > 3x+7
-2x > 5
x < 5/2

Negative method:
-x-2 > 3x+7
-4x > 9
x < -9/4

Absolute values and inequalities have a positive and a negative solution right?

 

[deswa1]

Wouldn't the answer be:

Positive method:
x+2 > 3x+7
-2x > 5
x < 5/2

Negative method:
-x-2 > 3x+7
-4x > 9
x < -9/4

Absolute values and inequalities have a positive and a negative solution right?

This should be -5/2 and no, not neccessarily

 

[seanieg89]

x < -9/4.

 

[seanieg89]

 

[ultimatecricker]

Thanks for the help. I forgot to consider that x < -2 means x+2 is negative and x>-2 means its positive. And also thanks for the advice about wolfram alpha. Its pretty cool. lol

 

[RivalryofTroll]

Thanks for the help. I forgot to consider that x < -2 means x+2 is negative and x>-2 means its positive. And also thanks for the advice about wolfram alpha. Its pretty cool. lol

Wolframalpha pwns

It can do limits, solve for x, differentiation, etc.

 

[planino]

could you also solve the same question by squaring both sides?

 

[planino]

Just use www.wolframalpha.com next time if you need to check answers.
Unless, you need full solutions.

That calculator thing really helped, thanks!

 

[RivalryofTroll]

could you also solve the same question by squaring both sides?

You can Square both Sides IF both sides are surrounded by absolute value signs:
E.g.
|x-3| < |2x-9|

 

[Autonomatic]

Thanks for the help. I forgot to consider that x < -2 means x+2 is negative and x>-2 means its positive. And also thanks for the advice about wolfram alpha. Its pretty cool. lol

Jesus, you are such a cricker. Expected more from you.

 

[ultimatecricker]

Jesus, you are such a cricker. Expected more from you.

And i would expect nothing from you