Answer:
Z = 1A + 2B + 3C + 4D
Step-by-step explanation:
Assuming A, B, C and D are the variables of the mathematical program, the function will be linear if it is represented as an addition of the variables affected by some coefficient, like 1, -2, 3, et cetera. Any other combination of the variables will result in a nonlinear program, e.g. multiplication or division of the variables, application of powers to the variables and so on.