The letter [katex] x[/katex] is used in algebra (Math) to mean a value that is not yet known.

Sometimes we call it variable or unknown.

In x+2=9, x is variable but we can work out if we try!

A variable does not have to be ‘ [katex] x[/katex] ‘, it may be ‘ [katex] y[/katex] ‘, ‘ [katex] z[/katex] ‘ ,’ [katex]w[/katex] ‘ or any letter named or symbol.

The above question could be asked what does x mean in math?

## Examples:1 what is x

Find the value of x, if x+9=4.

**Solution:**

[katex] x+9=4[/katex]

subtracting ‘9’ on both sides

[katex] x+9-9=4-9 [/katex]

[katex] x+0=-5 [/katex]

[katex] x=-5 [/katex]