The requirement is that every element in the domain must be connected to one - and one only - element in the codomain.
A classic visualization consists of two sets, filled with dots. Each dot in the domain must be the start of an arrow, pointing to a dot in the codomain.
So, the two things can't can't happen is that you don't have any arrow starting from a point in the domain, i.e. the function is not defined for that element, or that multiple arrows start from the same points.
But as long as an arrow start from each element in the domain, you have a function. It may happen that two different arrow point to the same element in the codomain - that's ok, the relation is still a function, but it's not injective; or it can happen that some points in the codomain aren't pointed by any arrow - you still have a function, except it's not surjective.
Answer:
It is expected that linearization beyond age 20 will be use a function whose slope is monotonously decreasing.
Step-by-step explanation:
The linearization of the data by first order polynomials may be reasonable for the set of values of age between ages from 5 to 15 years, but it is inadequate beyond, since the fourth point, located at 
, in growing at a lower slope. It is expected that function will be monotonously decreasing and we need to use models alternative to first order polynomials as either second order polynomic models or exponential models.
If the banana costs 10 dollars and you give 11 dollars, you have paid 110 percent of the cost.
Answer:
r = 0.
Step-by-step explanation:
The slope = (y2 - y1) / (x2 - x1)
So (r - (-3)) / (-4-2) = -1/2
(r + 3) / -6 = -1/2
2(r + 3) = 6
2r + 6 = 6
2r = 6 - 6 = 0
r = 0 (answer).
