# Unit 3

## Linear Relationships

### Proprotional Relationships

Linear relationships that go through the Origin (0,0)

## Slope

Also Known As:

• Rate Of Change
• Constant Of Proportionality
• Unit Rate
• Just call it SLOPE

### Equation of a line in 2 forms

We did the equation of a line in *Slope Intercept form * Y=MX+B

We also did the equation of a line in Standard Form Ax+By=C

for more details see Equation of a Line

## Special Lines

### Horizontal Lines

Horizontal lines in the coordinate plane represent situations where the Y value doesn’t change at all while the X value changes. For example, the horizontal line that goes through the point (0,13) can be described in words as “for all points on the line, the Y value is always 13.” An equation that says the same thing is y=13. The equation of this line is Y=5

### Vertical Lines

Vertical lines represent situations where the X value doesn’t change at all while the Y value changes. The equation X=-4 describes a vertical line through the point (-4,0). The equation of this line is X=8