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## Algebra 1

### Unit 5: Lesson 2

Graphing slope-intercept equations

# Graphing lines from slope-intercept form review

Slope intercept form is y=mx+b, where m is slope and b is the y-intercept. We can use this form of a linear equation to draw the graph of that equation on the x-y coordinate plane.
Slope intercept form is y, equals, m, x, plus, b, where m is slope and b is the y-intercept.
Slope-intercept form is nice when you're drawing graphs.
For example, imagine we're given the equation y, equals, 2, x, plus, 7 and asked to graph it.
Straight from the equation, we know the y-intercept is 7.
A first quadrant coordinate plane. The x- and y-axes each scale by one. The point zero, seven is plotted.
And we know the slope is 2.
start text, S, l, o, p, e, end text, equals, start fraction, delta, y, divided by, delta, x, end fraction, equals, start fraction, 2, divided by, 1, end fraction, equals, 2
So, for every one unit we go to the right, we must go up two units:
A first quadrant coordinate plane. The x- and y-axes each scale by one. A graph of a line goes through the points zero, seven and one, nine which are plotted. There is a horizontal segment from zero, seven to one, seven. There is a vertical line from one, seven to two, nine.
Here is our final graph:
A first quadrant coordinate plane. The x- and y-axes each scale by one. The equation y equals two x plus seven is graphed.

## Practice

Problem 1
Graph the following equation.
y, equals, minus, 4, x, minus, 1

Want more practice? Check out this exercise.

## Want to join the conversation?

• i need help beause i do not really under stand
• Eg. Equation: y=2x-4

Let x be 0, y= 2*0-4= 0-4= -4
Let x be 1, y= 2*1-4= 2-4= -2
Let x be 2, y= 2*2-4= 4-4= 0 and so on...

Then we get points: (0,-4), (1,-2), (2,0), ...
-----------------------------------------------------
Eg. Equation: y=(3/2)x-4

If x is 0, then y=(3/2)*0-4= 0 -4= -4
If x is 1, then y=(3/2)*1-4= 1.5-4= -2.5
If x is 2, then y=(3/2)*2-4= 3 -4= -1 and so on...

So we get points: (0,-4), (1,-2.5), (2,-1), ...
• i do not like this at all..
• This is the start of the largest empire of the world called math. This is important. If you don’t like it but want to work in any field related to math or science you will have a hard time. Revise it. Try to see the beauty of math. I would recommend Vi Harts videos
• math people... how do they get this stuff
• i know right is kinda hard
• when will we use this in our daily lives
• I can imagine carpenters using this but for most of us think of this as a foundation. These are building blocks to more complicated mathematical expressions. And even here, you can go a lifetime and not use it but if in your life you start to come across some math, it sure is good to have that foundation.

Think of it as though you have a chance to learn French. You probably will never need it until a great opportunity opens up for you in France (or Quebec :). Then you will wish you had learned it. In much the same way you are learning a new language with math the you one day you will find comes in really handy.
• I am so confused with the whole rise over run! it really is messing with my brain. I am so confused not just by the equation but I don't have a teacher to help me / guid me through this. And I don't have anyone to talk to help either. SO PLEASE HELP ME!
• Slope means how steep a line is. We know how steep a mountain is judging on how vertical it is. Similar to slope of lines. We judge it by how vertical it is and how much it increases in the vertical direction when compared to the horizantal direction. That's where rise over run came from.

Excellen question, by the way.
• I wish I could do more. Thats the only thing, Could we do more problems at a time or do we have to stick with 4?
• how to know when you have the correct numbers.