evaluate f (x)=5x^2 when x=3

To evaluate f(x) = 5x^2 when x = 3, we substitute x = 3 into the expression:

f(3) = 5(3)^2

f(3) = 5(9)

f(3) = 45

Therefore, f(x) = 5x^2 is equal to 45 when x = 3.