Let a, b and c be in a geometric sequence, then ac = b^2
Hence, (2k + 1)(7k + 6) = (3k + 4)^2
14k^2 + 19k + 6 = 9k^2 + 24k + 16
5k^2 - 5k - 10 = 0
5k^2 + 5k - 10k - 10 = 0
5k(k + 1) - 10(k + 1) = 0
(5k - 10)(k + 1) = 0
5k - 10 = 0 or k + 1 = 0
5k = 10 or k = -1
k = 2 or k = -1
The geometric sequence formed is
2(2) + 1, 3(2) + 4, and 7(2) + 6
5, 10, and 20
OR
2(-1) + 1, 3(-1) + 4, and 7(-1) + 6
-1, 1, and -1
Answer:
15cm and 45cm
Step-by-step explanation:
If one part is one third of the other, then the long one is three times as long as the short one.
If the short one has length x
x + 3x = 60cm
4x = 60cm
x = 15cm
So short one is 15cm and the long one is 3*15cm = 45cm
