Question from class: How do I make an equation from a line?

Way back in October we wrote equations in slope-intercept form or equations that look like y=mx+b where m and b are numbers. The number we put in place of m was the slope and b was the y-intercept.

So if we had this line:

We find the equation by finding the y-intercept or where the line crosses the y-axis and the slope. My line crosses at (0,3). Remember that the x value for the y-intercept will always be zero so we usually just say that the y-intercept is 3. So b=3

Then we find the slope. You have two options here, both start with choosing 2 points that are easy to find the coordinates of, meaning that the line crosses a point where the grid lines also cross. I chose (-1,0) and (2,9) because I liked them. There's no magic to the points I picked, any two would work.

Method 1: Pictures
In this method I am going to draw my rise and run between my points. The rise is blue, the run is 3. I count them out and set up my ratio of rise to run.

Method 2: Formula

Either way our slope is 3 so m=3. The equation is y=3x+3

I need it in different words or a few more examples.

Purple Math
Discovery Ed This link will find them for you, please use it wisely. An answer now isn't as valuable as one on the test. If you just use this to get the answer, you won't know what to do on the test.
Kahn Academy
Regents

Rotations on an outside point

Objective

Determine

Agenda

Brain Box
Questions
Video
Rotations Activity

Hints/Tips/Answers from Homework Questions

GR has a tip for rotating a shape. She says that you can rotate a shape by marking the length of a side on a piece of paper (cardboard works better) and poking hole on both ends with your pencil. Then you can place pencils in both holes and turn the paper the number of degrees you need. There is a similar method using a compass.

Rotations

Objective

Determine if shapes are congruent to their starting shape after they are rotated or reflected.

Agenda

Brain Box
Questions
POW
Rotations Activity

Hints/Help/Questions from class

Scientific Notation Reminders for Brain Box

Word problems and equations

Homework

All of 7.3 and 7.4 (due Friday)
POW Practice

Reflections

Objective

Determine if shapes are congruent to their starting shape after they are rotated or reflected.

Agenda

Brain Box
Reflections Activity

Hints/Trick/Help

If you are having trouble reflecting the shapes, try drawing it very dark then fold your paper very carefully on the line you are trying to reflect it across. Then rub on the back of the shape. This will give you a rough idea of where the shape ends up. After you do a few this way, you should start noticing something about the distance of each point from the line you are reflecting across. This pattern will take less time.

Homework

All of 7.3 and 7.4 (due Friday)
POW Practice

POW Quiz

Most of you did pretty good on the POW quiz! There are lots of us who are still trying to add x's and numbers. Like 6x+2=8x.  Remember, that doesn't work. It's like saying you have 6 candy bars and you put 2 sticks of celery with them and have 8 candy bars. Those are not the same things. If you didn't do well or you were confused, check out this video.

Some video reminders

Finding Slope

Finding y-intercept

Writing an equation in slope intercept form

Translations

It is ok for your shapes to overlap. If you do the first one on the homework right, it will overlap!

Objective

Find a pattern to make translations less work

Agenda

Bellwork
Activity
Start Homework

Activity

PDF (You will have to log in using your school email address.)
You have this on a half sheet of paper.
You will need these shapes again tomorrow.

Follow the instructions for the others.

Homework

ALL of 7.1 and 7.2 (Due Friday at the beginning of class)

I need help!

Where are the positives and negatives? or How do I plot points?

Virtual Nerd
Kahn Academy
Shmoop (not a video)

What is a translation? or How do I tell where the points went?

You may have called this a slide before, it means we move the shape over without turning it.
Math is Fun

And you can ALWAYS comment if that doesn't help.