Factor the denominator using potential zeros and synthetic division.
Potential zeros are ±1, ±2. Try 1
1|1 0 -3 2
| 1 1 -2
1 1 -2 0
So it works and thus we have factored the denominator as
(x-1)(x²+x-2)
(x-1)(x-1)(x+2)
(x-1)²(x+2)
The factor (x+2) does not become 0 when x=1, so if the
numerator could be a multiple of (x-1)² then that factor
would cancel into the top, creating a new function g(x)
which is equal to f(x) for all x except 1. Its value
at 1 would be defined, and thus f(x) would approach its
value as x->1. So we will see if there is a constant k
that would permit this cancellation. If so, we would
have this identity:
So the constant terms would have to be the same:
k=-2. And if we substitute k=-2:
So they will be identical if a = -2.
So we substitute for the numerator in
and get
Now, after canceling, we have the new function
g(x) which is identical to f(x) except for one
point:
Then the limit of f(x) as x -> 1 will equal g(1)
which is
Answer: a=-2 and the limit = -2/3.
Edwin