Question 3: In a mathematical programming model, if the objective functions and constraints are represented entirely by ________, then the model is regarded as a linear model.

Question 5: Still, Newton's model is quite sufficient for most ordinary-life situations, that is, as long as particle speeds are well below the ________, and we study macro-particles only.

Question 9: Similarly, a differential equation is said to be linear if it can be written with linear ________, but it can still have nonlinear expressions in it.

Question 10: Eykhoff (1974) defined a mathematical model as 'a representation of the essential aspects of an existing ________ (or a system to be constructed) which presents knowledge of that system in usable form'.