Evaluate the expression when a=3.
a^2+12

The answer is 21.

The correct answer is 21.

Step-by-step explanation:

To solve this problem, we simply substitute 3 for a in the expression.

Given the expression,

a^2 + 12

we should replace "a" with 3, as denoted by the problem, giving us:

(3)^2 + 12

Now, we simplify using the order of operations.  PEMDAS tells us that we should simplify what is in the parentheses first because it has an exponent.

9 + 12

Now, we can just add the two remaining terms together, giving us:

21

Therefore, the answer is 21.

Hope this helps!

justin bieber ml.