GRAPHING LINES

PLOTTING POINTS 4/8/13

What is an ordered pair?Two numbersIn parentheses Separated by a commaLike this: (4, 2)

ORDERED PAIRSWhat do they mean?

Represent a point on a coordinate plane.

1st number is x.2nd number is y.(x, y)

THE COORDINATE PLANEUsed to plot points and graph lines

and other functions.x moves left and right.y moves up and down.Positive moves

right or up.Negative moves

left or down.

TO PLOT POINTS:Start at the origin

(the center of the graph)Move left or right first (using x)Then, move up or down (using y)Count spaces, not lines!

EXAMPLESPlot and label each ordered pair.A. (2, 4)B. (-3, 1)C. (5, -2)D. (-4, -3)

YOU TRY!Plot and label each ordered pair.A. (-1, 3)B. (5, -1)C. (4, 2)D. (-5, -4)

GRAPHING LINES (WITH A TABLE) 4/10/13When you are given a filled in table:

The x and y values make ordered pairsPlot each point on the graphThen, connect them with a straight lineUse a RULER! No messy lines!!

EXAMPLEx y-4 5-2 30 12 -14 -3

FILLING IN YOUR TABLEWhen you are given an equation:

Choose x values for the table. (Or, they may be given to you)

Plug each # into the equation for x and find y.

Fill those y-values in the table.Then, plot the points and

draw the line.

EXAMPLE

x y

y = 2x - 3

FINDING SLOPE (FROM A GRAPH)

4/16/13What is slope?

The steepness/slant of a line.Also called “rate of change”

Real life examples:Ski slopeWater slideWheelchair ramp

Bigger slope means steeper line!

4 TYPES OF SLOPES

TO COUNT SLOPE:Count between any two points on a line.Slope = rise runRise: how far up or down

Run: how far left or right

EXAMPLE:Find the slope of the line.

EXAMPLE:Find the slope of the line.

EXAMPLE:Find the slope of the line.

EXAMPLE:Find the slope of the line.

YOU TRY!Find the slope of the line.

FINDING SLOPE (FROM 2 POINTS)

4/17/13Remember: ordered pairs represent

points on a graph.So, we can find slope using 2 ordered

pairs: (x1, y1) and (x2, y2)An m is often used to mean slope.

m = rise = change in y = y2 – y1

run change in x x2 – x1

SLOPE SONG(S)http://

www.youtube.com/watch?v=O3Yw6bGCM3c

http://www.youtube.com/watch?feature=player_detailpage&v=8TFf-p2cE70

EXAMPLES:Find the slope between each set of

points.(3, 4) and (5, 1)

(-3, 6) and (2, 6)

(4, 2) and (4, -3)

YOU TRY!Find the slope between:(7, 3) and (5, -1)

(6, 2) and (6, -2)