HEAR YOU GO BOYS LOL:}

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Arestaurant chef made 1 1/2 jars of pasta sauce. each serving of pasta requires 1/2 of a jar of sauce. how many servings of pasta will the chef be able to prepare using the sauce?