Question
Let a1, a2, ....,an be fixed real numbers and define a function f(x) = (x - a1)(x - a2)... (x - an). What is & $\mathop {\lim }\limits_{x \to {a_1}} f(x)$? For some $a \ne {a_1},\;{a_2}...{a_n},$ compute $\mathop {\lim }\limits_{x \to {a}} f(x)$