# How do you simplify and find the excluded values for 9/(15a-15)?

Mar 28, 2018

$\frac{3}{5 \left(a - 1\right)}$

#### Explanation:

Look for things you can cancel out.

Write as: $\frac{9}{15 \left(a - 1\right)}$

Divide top and bottom by 3

$\frac{3}{5 \left(a - 1\right)}$

We 'are not allowed' to have a 0 as the denominator of a fraction. The official name for this condition is that it is 'undefined'.

So the excluded value is $a = 1$

$\frac{3}{5 \left(1 - 1\right)} \to \frac{3}{5 \times 0} = \frac{3}{0} \leftarrow \text{ Undefined}$