Line V has a slope of -3/2

- Pick any two points to find the slope.

- Let's use points A and B

- Starting at point A counting three straight down for the rise

- Next count over two to the right to point B for the run.

- Finally, is the slope positive or negative ?

- As you move from left to right is the line sloping downward or upward?

- This line is sloping downward therefore it has a negative slope.

Line V intercepts the Y axis at point A therefore b equals 3

m = -3/2 ( slope)

b = 3 ( y intercept)

B

Slope Y Intercept Form

Hi Welcome to MooMooMath. Today we are going to look at the slope intercept form of a line. What form is that in? It is in y =mx + b In this formula m is the slope of the line and b is equal to the y intercept. What is a y intercept? The y intercept is where the y crosses the y axis. So the y axis is the long axis and in this example it crosses the y axis at positive 3 so I have a y intercept of positive 3 What is my slope? I pick two points on the line and I count. I go down three and over two. So I draw a right triangle and count three units down and two units across which is 3/2. I also notice that it is sloping down so it is a negative 3/2 Then all we do is plug an m and a b into the equation so I will plug negative 3/2 into my formula for the slope and 3 for b ( the y intercept) Let’s look at an overview.

Slope Intercept Form

Y=mx =b

m = the slope of the line. You find the slope by counting the rise over the run

b = y intercept This is where the line crosses the y axis

A

The slope intercept form is one method of expressing a linear equation. A linear equation is an equation of a straight line. In the slope intercept form you use the slope and the y intercept to express the line.

Write the linear equation of line a in slope intercept form.

Step 1. Use the points A and C Rise = 4,run = 2 slope = 4/2 = 2

Step 2. y intercept = 4

Step 3. Plug into slope intercept formula = y = 2x + 4

Write the linear equation of line a in slope intercept form.

Step 1. Use points A and C Rise = 2,run = -2 slope = 2/-2 = -1

Step 2. y intercept = -1

Step 3. Plug into slope intercept formula = y = -1x -1

You can also write the equation of a line in slope intercept form using two sets of points.

Step 1. Use the formula

2. Use the slope (m) and the x and y from one set of points and plug them into y=mx + b (You can use either set of numbers )

3.Solve for b

4. Plug m and b into slope intercept form formula

Using the points (27,-18) (-20,3) Write the equation of the line in slope intercept form.

Find slope

Plug the slope, and one order pair into the slope intercept formula

y=mx +b

3= -3(20) + b

Solve for b

3 = -60 + b

63 = b

Plug the slope and b into the formula.

Y = -3x +63

Here are two video links of real world slope problems. The first real life problem involves using slope intercept in order to calculate which phone plan has the best annual cost.

Value of y, the y axis runs up and down.

Slope.

Value of x, the x axis runs horizontally.

Where the line crosses the y axis, also called the y intercept.

I think it is helpful if you see the slope intercept form on a graph. Remember the m represents the slope,B is the y intercept, y is the vertical distance, and the x represents the horizontal distance.