lim x → a f ( x ) = L , {\displaystyle \lim _{x\to a}f(x)=L,} When you see this equation it means you are try to let x approaches a.
You may have a question why can't we just write it as
f ( a ) = L , {\displaystyle f(a)=L,}
some times we can't tell what is the F(a) equals to.
example 1
lim x → a f ( x ) = x 2 − 1 x − 1 {\displaystyle \lim _{x\to a}f(x)={x^{2}-1 \over x-1}}
