Flashcards
Straight-Line Graphs
Cards in this deck (5)
- 1Vertical and Horizontal lines: 'x=a' and 'y=a' x=a is a vertical line through 'a' on the x-axis y=a is a horizontal line through 'a' on the y-axisThe Main Diagonals: 'y=x' and 'y=-x'
y=x is the main diagonal that goes uphill from left to right
y=-x is the main diagonal that goes downhill from left to right - 2Other Lines Through the Origin: 'y=ax' an 'y=-ax' y=ax and y=-ax are the equations for a sloping line through the origin. The value of 'a' (known as the gradient) tells you the steepness of the line. The bigger the 'a' is, the steeper the slope. A minus sign tells you the slope is downhillLearn to spot straight lines from their equations:
All straight-line equations just contain 'something x, something y and a number' - 3Straight lines: x - y = 0 y = 2 + 3x 2y - 4x = 7 4x - 3 = 5yNot straight lines:
y = x3 + 3
1/y + 1/x = 2
x2 = 4 - y
xy + 3 = 0 - 4You might be asked to draw the graph of an equation in the exam. 1) Choose 3 values of x and draw a table 2) Work out the corresponding y-values 3) Plot the coordinates, and draw the lineDoing the 'Table of Values':
Draw the graph of y = 2x -3
1) Choose 3 easy x-values for your table
Use x-values from the grid you're given. Avoid negative ones if you can. - 52) Find the y-values by putting each x-value into the equation When x = 0, y = 2x -3 = (2x0) - 3 = -3 y = -3 When x = 4 y = 2x -3 = (2x4) -3 = 53) Plot each pair of x- and y- values from your table.
The table gives the coordinates e.g. (0, -3) and (4, 5)
Now draw a straight line through your points.
If a point looks wrong, check the y-values you worked out in the table, and that you've plotted the points correctly
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- Maths Flashcards on Straight-Line Graphs, created by Liffey Farrell on 13/05/2017.
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- Liffey Farrell
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