Mammoth Memory

Three-part inequalities on a number line

For an expression like

-1x<5

Split this into two i.e.

 -1x

And

x<5

-1x  this reads as -1  is less than or equal to x

 x<5 this reads x is less than 5

These can be shown on a number line as

Numbers in the sum show the beginning and end of the inequalities range

Or as:

You can draw it without the arrow too 

i.e. without an arrow.

 

Example 1

Write down the inequality shown in the diagram below:

In this example -5 and 5 are the 2 subjects in the sum including x so -5 and 5 make the range along the number line

Because x is the line between the two circles this can be read as:

The ring above -5  shows that -5  is less than x

(-5<x)

The ring above +5  shows that x is less than 5

(x<5) 

Joining the two together

-5<x<5

Answer:

 -5<x<5

 

Example 2

Write down the inequality shown in the diagram below:

in this example -4 is not less than x but is also less than 3

Because x is the line between the two inequalities this can be read as

The ring above -4  shows that -4  is less than x

(-4<x) 

The circle above the 3  shows that x is less than or equal to 3

(x3) 

Joining the two together

-4<x3 

Answer:

-4<x3