1. An Introduction to Straight Line Graphs Drawing straight line graphs from their equations. Investigating different straight line graphs.

2. y = x + 7 y = 3x – 5 y = 9 – 2x x y x y x y x y y = 2x 24 -4 1 2 10 -8 5 4 6 15 1 1113 8-6 2 5 1 110-2 3 4 5 319 0 Revising Substitution

3. -10 -8 -6 -4 -2 2 4 6 8 10 10 8 6 4 2 -2 -4 -8 -10 -6 Plotting Co-ordinates (1,2) x value y value x y (2, 4) (5, 10) (-4,-8) We have now revised substitution and co-ordinates. How could we draw the graph y = 2x?

4. Introduction to Straight Line Graphs - Solutions x-70146 y-11351115 x-5-2235 y-42101216 a) y = 2x + 3 b) y = 2x + 6 c) y = 2x – 4d) y = 17 – 2x Extension: Where does each graph intersect the y axis? Plot the points to draw the graphs. x02356 y-40268 x02468 y1713951

5. Solutions 2 6 8 10 4 12 14 -4 -8 -10 -6 -12 -14 2 -642 -2 -468-8 y = 2x + 3 y = 2x + 6 y = 2x – 4 y = x – 10 y = 2x – 7 What do the graphs y = 2x y = 2x + 3 y = 2x + 6 y = 2x – 4 y = 2x – 7 have in common? What are the differences? x y

6. More Substitution Substitution: we replace the variables in the equation with numbers. Replace the x with a number, for example, 3. Now our equation is: y = 2 3 We can now find the value of y.  Equation: y = 2x (This is the same as y = 2 x.) 