Question

A rational expression that will be undefined at x=1?

Answer 1

A rational expression of the form

`r(x)= (p(x))/(q(x))`
will be undefined for the zeros of the expression
`q(x)`. For an expression with a zero equal to 1, the simplest way is to use
`(x-1)` as a factor in
`q(x)`. In can be your only one, or you can mix in other factors.

But, so long as the denominator of
`r(x)` is equal to zero, as it is when
`q(x)=x-1`, the expression will be undefined at that point x, because it would involve division by zero.

You could use as your sample:


`(x-7)/(x-1)`

You can try to get fancy and square some factors or add in some radicals or trigonometric functions or anything else, so long as the 1 makes the denominator equal to zero!

Answer 2

This rational. expression will be undefined when x=1. 3x+2÷(-x+1)