Plotting Line and quadratic Graphs grade 7.pptx

LESSON: Plotting linear and
quadratic graphs
SUCCESS CRITERIA I can…
____ I can complete a table of values for a
function in the form ax + by = c or y = +c
__ I can draw a graph of a function from a
table of values.
COURSEBOOK/PRACTICE BOOK: 10.2

Substitution
• Calculate the value of y in each of the
following:
3y - x = 7 when x = 8
4y - x + 10 when x = 6
7y + 5x = 11when x = 13
67y + 2x = 77 when x = 5
y + 5x =31 when x = 6
4y - 2x = 2 when x = 4
10y + 3x = 5 when x = -10
5y + 2x = 9 when x = - 3

Plotting Line Graphs
• To plot the line y = x + 2, I need some
co-ordinates
• To get the co-ordinates, I use a table of values
• To find y, I substitute in values of x

x -2 -1 0 1 2
y
For the line y = x + 2
When x = -2
y = -2 + 2
y = 0
0
When x = -1
y = -1 + 2
y = 1
1 2 3 4
When x = 0
y = 0 + 2
y = 2

x -2 -1 0 1 2
y
Co-ordinates
0 1 2 3 4
(-2, 0) (-1, 1) (0, 2) (1, 3) (2, 4)
Now we have some co-ordinates, we can
plot them to draw the line!

0
-3
-2
-1
1
1
2
3
y
-5
-4
4
5
-5 -4 -3 -2 -1 2 3 4 5
X
X
X
X
X
X
x -2 -1 0 1 2
y
Co-ordinates
0 1 2 3 4
(-2, 0) (-1, 1) (0, 2) (1, 3) (2, 4)
y = x + 2

Quadratic Graphs
• Plot a graph of the equation ‘y = x2
+ 1
5
4
2
10
2
1
2
5
10
x2
+ 1
9
1
0
1
4
9
x2
3
1
0
-1
-2
-3
x
y = x2
+ 1

Quadratic Graphs
• Plot a graph of the equation ‘y = x2
+ 2x
y = x2
+ 2x
15
8
3
0
-1
0
3
x2
+ 2x
6
4
2
0
-2
-4
-6
2x
9
4
1
0
1
4
9
x2
3
2
1
0
-1
-2
-3
x

Quadratic Graphs
• Plot a graph of the equation ‘y = 3 – x2
-1
4
2
-6
2
3
2
-1
-6
3 – x2
9
1
0
1
4
9
x2
3
1
0
-1
-2
-3
x
y = 3 - x2

Plenary
Where in life might you see curved lines like the ones you have been
drawing?

Plotting Line and quadratic Graphs grade 7.pptx

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