How do you multiply #(56+11x-16x^2)*10/(15x^2-11x-56)# and state the excluded values?
The excluded values occur at the zeros of the denominator; let's try to factor. We seek a pair of factors of
Eventually we find
We could also have used the quadratic formula to find the zeros of the denominator, which are called poles.
The multiplication itself is rather vacuous due to the lack of cancelling.