Evaluate f(0)
We have 3 different function inside piecewise function
f(x) = 5 if x < 0
f(x)= x + 3 if 0 <= x <= 4
f(x) = 2x - 1 if x > 4
f(0) means we need to find f(x) when x=0
Now we check all the inequalities that satisfies x=0
0 <= x <= 4 means x = 0 to 4 but 4 is not included
x=0 satisfies the inequality 0 <= x <= 4
So we use f(x)= x + 3 to find f(0)
Replace x with 0
f(x)= x + 3
f(0)= 0 + 3 = 3
f(0) = 3