GRAPHING LINES

I N THIS SECTION : You will learn to graph ordered pairs You will learn to graph linear equations in two variables You will learn the standard form of a line. You will learn to graph a line by using the x and y intercepts. You will verify whether a point lies on a line.

C OORDINATE S YSTEM : ( X, Y ) Quadrant I (x,y) Quadrant II (- x,y) Quadrant III (- x,- y) Quadrant IV (x,- y) Origin (0,0)

A (2,3) B (-3, 1) C (-3, -5) D (2, -6) P LOTTING P OINTS : ( X, Y )

E (0,3) D (0,-3) F (3,0) G (-3,0) P LOTTING P OINTS : ( X, Y )

1) (0,4) 2) (-4,3) 3) (-4,-5) 4) (4,-5) 5) (4,3) 6) (0,4) Lift your pencil G RAPH D ESIGNS : W HAT DO THESE POINTS MAKE ?

STANDARD FORM OF A LINE:

L INEAR G RAPHS : Do these points lie on the same line?

L INEAR G RAPHS : Do these points lie on the same line?

L INEAR G RAPHS : Can you identify three points that lie on this line?

L INEAR G RAPHS : Can you identify three points that lie on this line?

V ERIFYING A P OINT ON A L INE : If you want to verify whether a point lies on the line, then you just need to plug in the values and test whether the equations works out: Therefore, (2,1) does not lie on this line.

V ERIFYING A P OINT ON A L INE :

F INDING THE X AND Y INTERCEPT : The x -intercept is the point where the line crosses the x -axis. The y -intercept is the point where the line crosses the y -axis.

F INDING THE X AND Y INTERCEPT : 1)2)

F INDING THE X AND Y INTERCEPT : 3)4) Do you notice a pattern with the x and y intercepts?

F INDING THE X AND Y INTERCEPT : 5)6) Do you notice a pattern with the x and y intercepts of horizontal and vertical lines?

F INDING THE X AND Y INTERCEPT AND G RAPH : 1) x -intercept: you set y = 0 and solve for x. 2) y -intercept: you set x = 0 and solve for y.

CST P REP P ROBLEMS :