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Graphing on Number Line Videos 7 videos

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ACT Math: Coordinate Geometry Drill 1, Problem 3. Solve the inequalities and choose the correct graph.

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ACT Math 1.3 Coordinate Geometry 304 Views


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Description:

ACT Math: Coordinate Geometry Drill 1, Problem 3. Solve the inequalities and choose the correct graph.

Language:
English Language

Transcript

00:02

For a good time, solve this shmoopy question.

00:05

Solve the inequalities and choose the correct graph: -4 ≤ 2y + 2 < 8.

00:11

And here are your potential options...

00:15

For starters, let's break this into 2 problems.

00:18

We'll start by lopping off 8 at the end there and just consider:

00:22

Negative 4 is less than or equal to 2y plus 2.

00:27

We subtract 2 from both sides to get:

00:29

Negative 6 is less than or equal to 2y.

00:32

Then we divide both sides by 2 to get:

00:35

Negative 3 is less than or equal to y.

00:38

So...let's put this part on the graph...

00:40

We start here at negative 3 ... and y is greater than or equal to this number so we're going

00:44

to move to the right...

00:46

And suddenly, we can eliminate B and D. Note that D has an open circle over negative 3...

00:50

...meaning that it's NOT equal to it but only greater than 3.

00:54

For our equation, it's greater than or equal... so the answer has to be A, C or E.

01:00

OK now consider the second part of the equation separately:

01:03

2y plus 2 is less than 8...

01:05

Subtract 2 from both sides and we have:

01:07

2y is less than 6.

01:09

Divide both sides by 2 and y is less than 3.

01:12

So let's put this part on the graph - and note that we need the open circle above

01:17

positive 3 here because it's not equal to it...

01:20

So the area we're talking about is between here and here.

01:23

Only A works and that's pretty much it.

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