September 13, 2011 At the end of today, you will be able to: - Make a graph representation of real life situations and predict results - Use Slope Intercept Form to write equations of lines - Use the Slope Formula to help write equations of lines. Warm-up: Draw an example for each symmetry rule. - Symmetric with respect to the origin. - Symmetric with respect to the x-axis. - Symmetric with respect to the y-axis. HW 1.3: Pg #39, 41, 46, 51-54, 69, , *Quiz 1 Thursday

Check HW 1.2 Pg. 22 #1-15odds, 21-25odds, 57, 59, 65, 67, 69, 71, 72 Next time I assign odds, please use your textbook to check the answers. 1a) yes, 1b) yes 3a) no, 3b) yes 5) (-1, 7), (0, 5), (1, 3), (2, 1), (5/2, 0) 7)(-1, 4), (0, 0), (1, -2), (2, -2), (3, 0) 9)xint = (±2, 0); yint = (0, 16) 11)xint = (6/5,0); yint = (0, -6) 13)xint (-4, 0); yint = (0, 2) 15) xint = (7/3, 0); yint = (0, 7) 21-25) sketch on board

Block A – finish circles

#57, 59, 65, 67, 69, 71, 72 57) x 2 + y 2 = 16 59) (x – 2) 2 + (y + 1) 2 65) ctr: (0, 0); r = 5 67) ctr: (1, -3); r = 3, plus graph 69) ctr: (1/2, 1/2); r = 3/ ) sketch on board

Group Activity Model it You only need one sheet of paper for the group. Assign each person in your group one of the questions. Answer part E together as a group.

To write an equation of a line you always need 2 things: a slope and y-intercept Slope Intercept Form y = mx + b

Lesson 1.3 Two ways to write an equation given a point and slope by graphing. Use y = mx + b Example 1: Write the equation of the line that goes through the point (-4,-1), with a slope of 3. First way, Graph it! Find all the points until you find the y-intercept (-4,- 1) y-int y = 3x + 11

Writing an equation of the line given a point and slope by using a formula How do you find the equation by using the formula?y = mx + b Example 2: Point (-4, -1), m = 3 -1 = 3(-4) + b solve for b -1 = b = b or y-int x, y y -intercept Since the slope = 3, y-int = 11 y = 3x + 11

You try! Write an equation of a line that goes through the point (-5, 4) and has a slope of 2.

Writing an equation in Slope Intercept Form, given two points Ex 3. Write an equation of a line that goes through (1, 2) and (3, -2)? There are 2 ways: 1) Graph it (1, 2) (3, -2) Identify the slope____ and y-intercept____ 4 y = -2x + 4

OR 2) Use the Slope Intercept Form y = mx + b Ex. 4 Write an equation of a line that goes through (1, 2) and (3, -2)? Step 1: Find the slope using Step 2: Plug values into y = mx + b, and solve for b (y-int) Use (1, 2): 2 = -2(1) + b 2 = -2 + b = b y = 2x + 4

One more practice problem! Write an equation of a line that goes through the points (-3, -2) and (1, 6). HW 1.3: Pg #39, 41, 46, 51-54, 69, , *Quiz 1 Thursday