Because limits have the unique ability to determine values at discontinuities, it is much more efficient to evaluate with limits than regular substitution. https://en.wikibooks.org/wiki/Calculus/Proofs_of_Some_Basic_Limit_Rules Before using limit properties, you must show that both limits and exist
Identity Rule
Constant Rule
if and for any constants then
Sums & Difference Rule
The limit of the sum, is the sum of the limits.
Scalar Product Rule
Product Rule
Quotient Rule
Power Rule
Limit of the power is the power of the limit