Answer: 512/9 and 6,144/81
Step-by-step explanation:
The sequence is:
18, 24, 32, 128/3, ...
Now, is easy to see that it is not an arithmetic sequence, so we can jump to see if this is a geometric sequence.
To see this, we must see at the quotient of two consecutive numbers in the sequence, and that quotient must be the same for any pair of consecutive elements.
24/18 = 1.33...
32/24 = 1.33...
(128/3)/32 = 1.33....
The quotient is constant, then this is a geometric sequence.
Then we can write the n-th term as:
Aₙ = Aₙ₋₁*1.33...
And we first should write 1.33 in a way that is easier to use:
1.33... = 1 + 0.33...
The left side can be writen as:
0.33... = 0.33...*(10/10) = (3.3.../10)
Now we can subtract the initial number:
(3.33..../10) - 0.33... = 3/10 = 0.33...*(9/10)
0.33... = (3*10)/(9*10) = 30/90 = 3/9
then we have:
1.33... = (1 + 3/9) = (9/9 + 3/9) = (12/9)
Then the two next terms are:
(128/3)*(12/9) = 128*4/9 = (512/9)
And the next term is:
(512/9)*(12/9) = (6,144/81)
Then the first six terms are:
18, 24, 32, 128/3, 512/9, 6,144/81
