Let a1,a2,.....,an be fixed real numbers such that f(x)=(x−a1)(x−a2)....(x−an) What is limx→a1 f(x)? For a≠a1,a2,....,an compute limx→af(x).
limx→a1f(x)\
⇒(x−a1)(x−a2)....(x−an)
[Putting lim it x→a1]
⇒(a1−a1)(a1−a2)....(a1−an)
⇒0
And, limx→af(x)
⇒limx→a(x−a1)(x−a2)...(x−an)
[Putting lim it x→a]
⇒(a−a1)(a−a2)....(a−an)