Question 34521
{{{ ((x^2+10x-11)/(x^2-1))    *   ((x+1)/(x+11)) }}}
Factor the numerator and denominator of the first fraction
{{{ ((x-1)(x+11)/(x-1)(x+1))    *   ((x+1)/(x+11)) }}}
Multiply straight across
{{{ ((x-1)(x+11)(x+1) /(x-1)(x+1)(x+11)) }}}       
Notice the numerator is the same as the denominator.

Anything divided by itself equals 1