How do you evaluate f x equals 3x plus 7 at f 4?

Answer 1

Evaluating a function called f(x) at f(4) basically means you set x = 4 in f(x) and solve. In other words, you solve the expression for x = 4. In this case: f(x) = 3x + 7
f(4) = 3(4) + 7
f(4) = 12 + 7
f(4) = 19
So, if you evaluate this function for f(4), you get 19.