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 $\mathop {\lim }\limits_{x \to {a}} f(x)$

Answer

Here f(x) = (x – a1) (x – a2)… (x – an)
Now $\mathop {\lim }\limits_{x \to {a_1}} f(x) = \mathop {\lim }\limits_{x \to {a_1}} (x - {a_1})(x - {a_2})...(x - {a_n})$
= (a1 – a1) (a1 – a2) … (a1 – an)
= 0 × (a1 – a2) … (a1 – an) = 0.
Also $\mathop {\lim }\limits_{x \to a} f(x) = \mathop {\lim }\limits_{x \to a} (x - {a_1})(x - {a_2})...(x - {a_n})$
= (a – a1) (a – a2) … (a – an)

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free