Question

marks)
9 (b). The first two terms of an arithmetic progression are shown.
р
5p
The sum of the first three terms is 90
Work out the value of p.

Answer 1

9514 1404 393

Answer:

  p = 6

Step-by-step explanation:

The difference between the first two terms is ...

  5p -p = 4p

Since this is an arithmetic sequence, the next term will be 4p more than the last term:

  5p +4p = 9p

Then the sum of the first three terms is ...

  p + 5p + 9p = 90

  15p = 90 . . . . . . . . . . collect terms

  p = 6 . . . . . . . . . . . . divide by 15

_____

The first three terms are 6, 30, 54.