What is the value of 3² + 4²?

To determine the value of 3² + 4², we begin by calculating each term separately.

First, 3² means 3 multiplied by itself, which equals 9. Next, we calculate 4², which is 4 multiplied by itself, resulting in 16.

Now, we add these two results together:

9 + 16 = 25.

Therefore, the value of 3² + 4² is 25, which corresponds to the correct choice. This calculation illustrates the basic principles of squaring numbers and then summing them, a fundamental concept in mathematics that illustrates the use of exponentiation and addition.