4. Look at each set of points. If all x-coordinates are different, it is a function. If the same number shows up more than once as an x-coordinate, it is not a function.
Here are the x-coordinates for each choice:
a. 0, 1, 2, 3 All are different. This is a function.
b. 0, 0, 2, 2 There are two zeros and two twos. Not a function.
c. 0, 1, 2, 3 All are different. This is a function.
d. 0, -1, -2, -3 All are different. This is a function.
5. The rate of change is the slope.
a. slope is -3
b. slope = (9 - 7)/(0 - (-1)) = 2
c. 3y + 9x = 10
3y = -9x + 10
y = -3x + 10/3
slope = -3
d. slope = (14 - 10)/(10 - 6) = 4/4 = 1
The greatest slope is 2 in option b.
