^ He is wrong!!! The actual answer is 25!!!
First substitute the value of the variable into the expression. P.S you will need to add parenthesis in order to solve this equation correctly.
(a + b)^2= (2 + 3)^2
Now start with solving inside of your parenthesis (PEMDAS)
(2+3)= 5
Now take the number 5 and raise it to the power of two
5^2= 25
Final Answer: 25