Question

Mrs. Jackson gives the table below to her students.

In order for the function to be linear, what must a be and
why?
Х
4
5
6
y
26
23
a = 22 because the rate of change is 1.
a = 20 because the rate of change is 3.
a = 22 because the rate of change is -1.
a = 20 because the rate of change is -3.
a

Answer 1

a = 20 because the rate of change is -3

Explanation:

In order for the function to be linear, sequential values of x must match values of y that have the same first differences. Here, 23-26 = -3, so we must have a-23 = -3. That is to say, the value of "a" must be 20.

The "rate of change" is the ratio of the differences in y to the differences in x. Here, that is -3/1 = -3. The appropriate choice is ...

a = 20 because the rate of change is -3