Question

When can you use direct substitution when finding limits.

Answer 1

You can use direct substitution when you can actually get a value when the number your approaching gets plugged in for x. You can't use direct substitution when you get an indeterminate form. A common indeterminate form is 0/0, but there are many others
.

Answer 2

\[\lim_{x \rightarrow a}f(x)\]
You can use direct substitution when f(x) is continuous at a.

Answer 3

oh yeah.. continuous i remember that now. thank you both!