The points on this graph represent the first five terms of an arithmetic sequence. The height of each point is its distance from the x-axis, or the value of the y-coordinate of the point.

a. Find u0, the y-coordinate of the point preceding those given.
b. How many common differences (d's) do you need to get from the height of (0, u0) to the height of (5, u5)?
c. How many d's do you need to get from the height of (0, u0) to the height of (50, u50)?
d. Explain why you can find the height from the x-axis to (50, u50) using the equation u50 = u0 + 50d.
e. In general, for an arithmetic sequence, the explicit formula is un =

20 d= 5 3 10