Evaluate the function f(x) = x^2+ 5x for the given value of x. Simplify your answer.

To evaluate the function f(x) = x^2 + 5x for a specific value of x, let's choose x = 3.

f(3) = (3)^2 + 5(3)
f(3) = 9 + 15
f(3) = 24

Therefore, f(3) = 24.