2. Determine if the following point is on the graph of the equation. 2x – y = 6; (2, 3) Step 1: Plug the given points into the given equation. 2(2) – (3) = 6 Step 2: Simplify. 4 – 3 = 6 1 = 6 Step 3: If the answer is true, the point is on the graph. If the answer is false, then the point is not on the graph. Since 1 =6 is false, the point (2, 3) is not on the graph of this equation.

3. Intercepts The x-intercept is where the graph crosses the x-axis. What’s special about the coordinates of this point?  The ordinate (y value) is zero. The y-intercept is where the graph crosses the y-axis. What’s special about the coordinates of this point?  The abscissa (x value) is zero. An intercept is the point at which the graph crosses or touches one of the coordinate axes.

4. Examples: Find the intercepts 1. x 2 + y - 9 = 02. y =

5. Symmetries x – axis symmetry: for every point (x, y) on a graph, the point (x, -y) is also on the graph y – axis symmetry: for every point (x, y) on a graph, the point (-x, y) is also on the graph Origin symmetry: for every point (x, y) on a graph, the point (-x, -y) is also on the graph

6. Examples: Plot each point, then plot the point that is symmetric to it with respect to the a.) x – axis, b.) y – axis, and c.) origin. 1. (-2, 1)2. (4, -3)

7. To Test for Symmetry x-axis symmetry: Replace y with –y in the equation y-axis symmetry: Replace x with –x in the equation Origin symmetry: Replace x with –x and replace y with –y in the equation In each case, if you get the exact same equation back, you have that type of symmetry.

8. Examples: Test for symmetry 1. x 2 + y - 9 = 02. y = Homework: p. 18-19 #2-44 even