Answer
$\lim\limits_{x \to 1^-}$f(x)=3
Look and see what happens to y as x goes to 1 from the left hand side. y goes to 3.
$\lim\limits_{x \to 1^+}$f(x)=7
Look and see what happens to y as x goes to 1 from the right hand side. y goes to 7.
Work Step by Step
Under the lim, we see that x goes to $1^-$. The negative sign means that x is approaching 1 from the left hand side. Everything to the right of 1 isn't considered. Then we have f(x)=3 which means y is going to 3.
This time, the limit is going to $1^+$. The positive sign means that x is approaching 1 from the right hand side. Then we have f(x)=7 which means y is going to 7.
