Chapter overview 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

Measures

Lines and angles

Drawing shapes

Trigonometry

Probability

Statistics

Maths

# Drawing straight line graphs 0%

Summary

# Drawing straight line graphs

## ​​In a nutshell

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.

## What is a straight line graph?

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.

## Plotting points

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.

##### Example 1

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:

## Using only two points

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!).

##### Example 2

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:

## Using more than 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.

##### Example 3

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.

## Want to find out more? Check out these other lessons!

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