Hi L;
The format of these equations is...
y=mx+b
m is the slope. Slope is also called riseoverrunthe change of y divided by the change of x.
b is the yintercept, the value of y when x=0.
y= x + 1
slopem=1
yinterceptb=1
This line has a positive slope of 1. As the value of y increases by one unit, the value of x
increases by one unit.
At the point of (0,1), this line crosses the yaxis.
y= 3x + 9
This line has a negative slope of 3. Normally, this would be written as 3/1. In this circumstance, the field of mathematics contradicts itself. It is actually 3/1. As the value of y
increases three units, the value of x decreases by one unit.
At the point of (0,9), this line crosses the yaxis.
We have established one point as well as the slope of each line. This should be adequate to graph each line. It would be nice if we also know at what point these lines intersect...
y= x + 1
y= 3x + 9
Let's subtract the latter equation from the first...
y= x + 1
(y= 3x + 9)
0=4x8
4x=8
x=2
Let's establish the value of y...
y= x + 1
y=2+1
y=3
The lines intersect at (2,3).
Let's verify this with the other equation...
y= 3x + 9
3=3(2)+9
3=6+9
3=3
12/27/2013

Vivian L.