Substitute to complete a table of values

In Sub In, we learnt how to substitute number values into equations to find a final value. Now we're going to use the same process and substitute one value into an equation to find the other unknown.

For example, if we were given the equation $y=2x$y=2x and asked to find the value of $y$y when $x=8$x=8, we would substitute in $8$8 for $x$x into the equation to work out that $y=2\times8$y=2×8$=$=$16$16. 

A table of values is a nice, easy way to display this relationship between $x$x and $y$y values. Later on, we will use the $x$x and $y$y values as sets of coordinates to plot on a number line. But let's start by working through some examples and learn how to complete a table of values. Let's use the same equation as before, $y=2x$y=2x, to complete the following table.

$x$x	$-1$−1	$0$0	$1$1	$2$2
$y$y

We can substitute each of these $x$x values into the equation.

$2\times\left(-1\right)=-2$2×(−1)=−2 

$2\times0=0$2×0=0

$2\times1=2$2×1=2 and $2\times2=4$2×2=4.

Let's write in these values to complete the table.

$x$x	$-1$−1	$0$0	$1$1	$2$2
$y$y	$-2$−2	$0$0	$2$2	$4$4

Do you notice how as the $x$x values increase by one, the $y$y values increase by two? Think about the rule and why this is the case.

 

Examples

question 1

question 2

question 3