1. 2.5 Linear Equations

2. Graphing using slope and y-intercept (section 2.4)
Graphing using table
Graphing using slope and y-intercept (section 2.4)
Graphing using x-intercept and y-intercept (section 2.5)
X-intercept
y-intercept

3. To find x-intercept, set y = 0, solve for x
To find y-intercept, set x = o, solve for y
Ex1) 3x + 2y = 12

4. Ex2) y = -4x + 5
Ex3) x + (1/2)y = -8

5. Ex: y = 2x - 4, we have x-intercept (2, 0) y-intercept (0, -4)
To graph a linear equation, find x-intercept and y-intercept, plot them then connect the points.
Ex: y = 2x - 4, we have x-intercept (2, 0)
y-intercept (0, -4)
(2,0)
(0,-4))

6. Standard Form of Linear Equation:
Ax + By = C
Slope-Intercept Form:
y = mx + b
Point-Slope Form:
y – y1 = m (x – x1)

7. Two lines are parallel if they have the same slope
Ex: y = 3x + 4
y = 3x - 2
Two lines are perpendicular if the product of their slopes = -1 (or one slope is the opposite reciprocal of the other slope).
Ex: y = (1/3) x
y = -3x - 2

8. Are these lines parallel, perpendicular, or
neither?
y = (-3/2)x + 4
2y + 3x = 1
y = 5x
5y + 15 = x
3) x + 3y = 3
3x = 1 + y

9. Horizontal line:
slope = 0
Ex: y = 4 or y = -2
Vertical line:
slope is undefined
Ex: x = 4 or x = -2