Question

F(x) = x2+3x+2 x2+5x+4 Why is there no zero at x = –1?

Answer 1

You could rewrite
`F(x)` as


`(x^2+3x+2)/(x^2+5x+4)=((x+1)(x+2))/((x+1)(x+4))`

and be tempted to cancel out the factors of
`x+1`. But this cancellation is only valid when
`x\\eq-1`.

When
`x=-1`, you end up with the indeterminate form
`\frac00`, which is why
`-1` is not a zero.