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Mathematics 21 Online
OpenStudy (explainitlikeimfive):

Solve the inequality. Graph the solution set. 2r – 9 – 6

OpenStudy (explainitlikeimfive):

OpenStudy (explainitlikeimfive):

\[2r-9 \ge - 6\]

OpenStudy (mathstudent55):

Is it >, >=, <, or <=?

OpenStudy (goldphenoix):

Alright. So we want to find r. SO we want to get rid of -9. How can we get rid of -9?

OpenStudy (explainitlikeimfive):

divide some numbers by 3

OpenStudy (goldphenoix):

No. We want to get rid of -9, or cancel out. How can we cancel out -9?

OpenStudy (explainitlikeimfive):

That was my only plan, I have no idea.

OpenStudy (goldphenoix):

What's the opposite of subtraction?

OpenStudy (explainitlikeimfive):

addition

OpenStudy (goldphenoix):

So how can we use addition to cancel out -9? As in, what number add to -9 give us 0?

OpenStudy (explainitlikeimfive):

9

OpenStudy (goldphenoix):

Good. -9 + 9 = 0 What's -6+9 ?

OpenStudy (explainitlikeimfive):

3

OpenStudy (goldphenoix):

\[\large \large 2r \ge 3\] ^So we have that so far, correct? Does it make sense so far?

OpenStudy (explainitlikeimfive):

Yes

OpenStudy (goldphenoix):

Alright. So how can we get r by itself?

OpenStudy (explainitlikeimfive):

add -2

OpenStudy (goldphenoix):

Well. 2r is a coefficient. Which mean it is a number multiply by a variable. So another way of writing 2r is 2 * r. We want r by itself, so we want to get rid of 2. To get rid of 2, we must use the opposite operation. So what's the opposite of multiplication?

OpenStudy (explainitlikeimfive):

Division

OpenStudy (goldphenoix):

So we do 2 divided by 2, which would give us 1. Now, what's 2 divided by 3?

OpenStudy (goldphenoix):

By the way, keep it as fraction form for now.

OpenStudy (goldphenoix):

Also, I mean 3 divided by 2*

OpenStudy (explainitlikeimfive):

2/3

OpenStudy (goldphenoix):

3 divided by 2* My bad.

OpenStudy (explainitlikeimfive):

3/2

OpenStudy (goldphenoix):

Great. So now what does our inequality looks like?

OpenStudy (explainitlikeimfive):

3/2

OpenStudy (explainitlikeimfive):

r = 3/2

OpenStudy (goldphenoix):

Where's our r? o_O Did r vanish into thin air?

OpenStudy (goldphenoix):

Well. It's not equal, since it's an inquality. It's r greater than or equal to 3/2.

OpenStudy (goldphenoix):

You can leave it as 3/2 or you can put it into a mixed number or a decimal.

OpenStudy (explainitlikeimfive):

\[r \ge \frac{ 3 }{ 2 }\]

OpenStudy (goldphenoix):

Yes. I prefer mixed number than improper fraction, since improper fraction is... improper. You know what 3/2 in mixed number form?

OpenStudy (explainitlikeimfive):

\[1\frac{ 1 }{ 2 }\]

OpenStudy (goldphenoix):

Great. So you can write it as r >= 1 1/2

OpenStudy (explainitlikeimfive):

ok

OpenStudy (goldphenoix):

I hope this help! :)

OpenStudy (explainitlikeimfive):

Thanks

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