Replace x with 2 and solve:
2^2 + 4(2) = 4 + 8 = 12
Replace x with 3 and solve:
3^2 + 4(3) = 9 + 12 = 21
The difference between the two answers is : 21 -12 = 9
The difference between the two inputs is 3-2 = 1
The rate of change is the change in the answers I’ve the change in the inputs:
Rate of change = 9/1 = 9