The sequence 6, -9, x , y is such that the first three terms form an arithmetic sequence and the last three terms form a geometric sequence. Find x and y.
Express answer as (x , y).
+981 If the first three terms form an arithmetic sequence, the arithmetic sequence goes: 6, -9, x
Therefore, 6 - (-9) = -9 - x, x = -24
Since the last three terms is a geometric sequence, the geometric sequence goes: -9, -24, y
Therefore, -24/(-9)=y/(-24)
After you solve for y, you get your answer.
Gavin,
+981 If the first three terms form an arithmetic sequence, the arithmetic sequence goes: 6, -9, x
Therefore, 6 - (-9) = -9 - x, x = -24
Since the last three terms is a geometric sequence, the geometric sequence goes: -9, -24, y
Therefore, -24/(-9)=y/(-24)
After you solve for y, you get your answer.
Gavin,
