An excluded value of x≠-6 implies that x=-6 is the only value for which the expression is defined. But if x≠13 is excluded then x=13 is the only value for which the expression is defined. Since x cannot be both -6 and 13, I think the excluded values are x=-6 and x=13, in which case an example would be 1/((x+6)(x-13)) or 1/(x²-7x-78).