Warm UpSolve for y when x = 0. 1. y = 8x – 2

2. 6x + y = 2

3. 2x – 3y + 6 = 0

4. 4x – 2y = 1

5. -7x – 14y -5 = 0

Advanced Algebra Trigonometry Appendix B

Objective: SWBAT graph equations by using the x and y-intercepts and point plotting.

Linear Equations

A linear equation in slope intercept form has the form:

y = mx + b

(x, y) = a solution of the equation (an ordered pair)m = slope (steepness of a line)

b = y-intercept * The graph of a linear equation is a line*

x-intercepts and y-interceptsx-intercept:

Where the line crosses the x-axis. (x, 0). To find the x-intercept, plug in zero for y and solve.

y-intercept:Where the line crosses the y-axis. (0, y). To find the y-intercept, plug in zero

for x and solve.

Linear EquationsFind four solutions for the following linear equations. Then graph the

equation.

1. y = 2. y = 4x – 1 43

5x

x-intercepts and y-interceptsFind the x and y-intercepts of the following equations:

1. 4x – 5y = 20 2. -6x + 8y = -36

How to Graph an Equation1. Isolate (get alone) one of the variables if possible (usually

y)

2. Find the x and y intercepts by plugging 0 in for y and then for x like we did on the previous screen (sometimes easier to do this before you isolate a variable)

3. Make a table of values choosing four x values and find corresponding y values (if you isolated x then choose some y values and find corresponding x values)

4. Plot these points and join in a smooth curve or line

Linear EquationsGraph the linear eqution:

1. 3 + y = -2x

x2 + y2 = r2

Find the x and y-intercepts of:x2 + y2 = 9

Graph the equation. What does it make?

Homework

Page 447-449# 21, 22, 23 and 43-46 (all)