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Chapter overview
Learning goals
Learning Goals
Maths
Types of numbers
Number calculations
Fractions, decimals and percentages
Algebraic manipulation
Formulae and equations
Straight line graphs
Other graphs
Ratio
Proportion
Rates of change
Shapes
Properties of shapes
Lines and angles
Drawing shapes
Trigonometry
Probability
Maths
Summary
Straight lines can be plotted by joining up points marked on a coordinate grid. Only two points are needed to plot a straight line, but more than two points can be used when sketching a straight line graph to add precision.
A graph is a series of points joined up, even if the points are not clearly marked (for example, with a cross). A straight line graph is the same, with the condition that these points sit in-line with each other. Another word for a straight line graph is a "linear" graph.
Points can be plotted from the origin on a coordinate grid. You move horizontally for the $x$ coordinate value, then vertically for the $y$ coordinate value.
Plot the point $(-2,7)$.
Starting from the origin, which is at $(0,0)$, move horizontally by $-2$, which means going to the left by $2$.
Then, move vertically by $7$, which means going up by $7$. Mark this point:
If you plot two points, you can join them up with a straight line. The line should continue infinitely beyond these two points (in theory - obviously you can't actually draw an infinitely long line!).
Draw a straight line that connects the points $(1,3)$ and $(4,0)$.
Start by plotting these two points:
Then join these points up, ensuring the line continues past the two points:
Sometimes you will be asked to plot many points and to join them up with a line. For now, this is how you will plot a straight line graph.
Consider the table below, which gives a series of coordinates for points.
$x$ | $-1$ | $0$ | $1$ | $2$ | $3$ |
$y$ | $-6$ | $-4$ | $-2$ | $0$ | $2$ |
Plot these points and check that they all sit in a straight line.
The points you have are $(-1,-6)$, $(0,-4)$, $(1,-2)$, $(2,0)$ and $(3,2)$. Plotting these and connecting them looks like:
See that all of these points are indeed in-line with each other.
Straight lines can be plotted by joining up points marked on a coordinate grid. Only two points are needed to plot a straight line, but more than two points can be used when sketching a straight line graph to add precision.
A graph is a series of points joined up, even if the points are not clearly marked (for example, with a cross). A straight line graph is the same, with the condition that these points sit in-line with each other. Another word for a straight line graph is a "linear" graph.
Points can be plotted from the origin on a coordinate grid. You move horizontally for the $x$ coordinate value, then vertically for the $y$ coordinate value.
Plot the point $(-2,7)$.
Starting from the origin, which is at $(0,0)$, move horizontally by $-2$, which means going to the left by $2$.
Then, move vertically by $7$, which means going up by $7$. Mark this point:
If you plot two points, you can join them up with a straight line. The line should continue infinitely beyond these two points (in theory - obviously you can't actually draw an infinitely long line!).
Draw a straight line that connects the points $(1,3)$ and $(4,0)$.
Start by plotting these two points:
Then join these points up, ensuring the line continues past the two points:
Sometimes you will be asked to plot many points and to join them up with a line. For now, this is how you will plot a straight line graph.
Consider the table below, which gives a series of coordinates for points.
$x$ | $-1$ | $0$ | $1$ | $2$ | $3$ |
$y$ | $-6$ | $-4$ | $-2$ | $0$ | $2$ |
Plot these points and check that they all sit in a straight line.
The points you have are $(-1,-6)$, $(0,-4)$, $(1,-2)$, $(2,0)$ and $(3,2)$. Plotting these and connecting them looks like:
See that all of these points are indeed in-line with each other.
Straight line graphs
FAQs
Question: What is a straight line graph?
Answer: A straight line graph, also called a linear graph, is a line that connects a (possibly infinite) series of points that sit in-line with each other.
Question: How many points do you need to plot a straight line?
Answer: Only two points are needed to plot a straight line graph.
Question: What is a linear graph?
Answer: This is another name for a straight line graph.
Theory
Exercises
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