1. Check hmwk. w/book need graph paper
Warm-up
X = 3 is what type of line when graphed?
Y = -4 is what type of line when graphed?
What are the equations of the horizontal & vertical lines that pass through the point (2, 6)?
Questions on last night’s homework?

2. 4.2 Linear Equations with 2 Variables
A linear equation is a 2 variable equation where both variables are to the 1st power.
Linear Equation: y = x, y = 2x-3 [Lines]
Non-Linear Equation: y = x2 , y = 2x3 - 4
All linear equations make a straight line when they are graphed. Each point that makes up the line is a solution to the equation. (infinite solutions)

3. GOAL: Finding points to a linear equation.
A solution to a linear equation is written as an ordered pair (x,y).
When you graph a linear equation you ALWAYS find at least 3 solutions to the equation…why???
So you can tell exactly where the line goes!

4. Steps to graph a linear equation:
Find at least 3 points
Graph the points
Draw a straight line through the points - USE A RULER
Not a straight line – wrong graph!

5. Substitution is the key to find points on linear equations.
Pick an x- coordinate for your point.
Substitute that in for x in the equation.
Solve for y, your y-coordinate of the point.
K.I.S.S.
Ex: y = x+4 x y y= y=
0 4
3 points

6. Linear equation points
Find 3 points for each line & write your results in a t-chart
Y = 5 - 3x
-4x + 5 = y
3x – y = 2
Y = ½(6 – 4x)
-x + 3 = y
Y = -(x – 3)

7. Which points lie on the line?
Decide which of the two points lies on the line.
2x +3y = 10
A. (2,2)
B. (3,1)
2y – 4x = 6
A. (1, 4)
B. (-1, 1)
6y – 3x =-9
A. (3, 0)
B. (-2, -1)
-5x – 8y = 15
A. (-3, 0)

8. Solve 4y – 6x = 10 for y 4y – 6x = 10 4y – 6x + 6x = 10 + 6x
Y = x 4

9. Let’s practice

10. Write summary