Help: Which way to shade for graphs of linear inequalities?

[MissSnickers]

How do I know which way to shade on the number line after completing a simple open sentence*?

* -7(9w + 8) < 70

 

[tkhunny]

Do not ever be confused again. Just try something -- something easy. In this case, how about w = 0? If it works, shade the side with w = 0 in it.

 

[MissSnickers]

But in my math book the answer came out to -1 and they shaded to the right :?:

 

[stapel]

But in my math book the answer came out to -1

The answer to what "came out to -1"? Please clarify. Thank you.

Eliz.

 

[tkhunny]

Re: Help: Which way to shade for graphs of linear inequaliti

-7(9w + 8) < 70

I think you're just not quite paying attention.

Solve the inequality.

-7(9w + 8) < 70

Divide by -7

9w + 8 > -10

Subtract 8

9w > -18

Divide by 9

w > -2

This tells us we have a break at w = -2.

Now the question is, which side do we shade? If it is not obvious, try the "Easy" test.

-7(9w + 8) < 70

Should we shade the side with w = 0?

-7(9(0) + 8) < 70 ???
-7(8) < 70 ???
-56 < 70 -- Yes!!!

You don't really care what the book says. You have confidence in your skills and consistency. If you write your steps VERY CLEARLY, you can prove your answer, even in the face of everyone else in class getting the wrong answer.