tentukan rumus fungsix plizz dijawab kakak!!

f(x) = ax + b
f(0) = a(0) + b = 3 -> b = 3 
f(1) = a(1) + b = 4
       = a + 3 = 4
       => a = 1
f(x) = ax + b
f(x) = 1x + 3
f(x) = x + 3