The Linear Equation

The Linear Equation

The Linear Equation is the Algebra's students oldest friend

The linear equation can be written in three different forms.  Those forms are Standard form, Point Slope form and Y intercept form.  We will start with focusing our efforts with Y intercept.  Y intercept is written in the form y = mx+b

Where m is the symbol for slope

X is the value you select to find a y cooridnate 

b is the Y intercept, hence Y intercept form. 

In order to find the slope of a line you must pick any two points on a graph. Lets look at the graph above and select two points.  You can select any two points you want but let us look at          ( -1  , 8) and ( 1 , 2).

Now lets label our points x1, y1 and x2, y2.  Lets make -1=x1, 8=y1, 1=x2 and 2=y2.

Now that you have (x1,y1)=(-1 , 8) and (x2,y2)=(1 , 2) we need to use the slope form formula that is written above and plug our numbers into the equation.  So we should get something that looks like this

(2-8)/(1-(-1)) = -6/2 = -3 therefor our slope for this line is a -3.

Now that we know the slope which is our m value.  We must now look back at the graph to see were the line crosses the Y axis.  This will be our b value. 

Now we know a few things

1. m = -3

2. b = 5

3. We know the form of the equation is y = mx + b.

We can now plug them into into the equation to get.

y = -3x +5

Now we know how to use y intercept form.  Look for the other two books to help you with point slope form and standard form. I hope you enjoyed learning about the y intercept form.