Answer:
364/27
Step-by-step explanation:
9, 3, 1, ... is a geometric sequence with common ratio r = 1/3.
The nth term is a1rn-1.
If a1rn-1 = 1/27, then 9(1/3)n-1 = 1/27
32(3-1)n-1 = 3-3
3231-n = 3-3
33-n = 3-3
3-n = -3
n = 6
The sum, Sn, of the first n terms of a geometric sequence is given by Sn = a1(1 - rn) / (1 - r).
So, 9 + 3 + 1 + ... + 1/27 = S6 = 9(1 - (1/3)6) / (1 - 1/3)
= 9(1 - 1/729) / (2/3)
= (27/2)(728/729) = 364/27
The answer is all real numbers
domain is easy like that
Let x be the number of child tickets he bought
Let y be the number of adult tickers he bought
① x+y=7 (child tickets+adult ticket=7 tickets in total)
② 2x+4y=24 (price of child tickets+price of adult tickets=$24 in total)
We may simply the second equation since all of the coefficients are divisible by 2.
① x+y=7
② x+2y=12
We can now use elimination by multiplying the second equation by -1.
② -(x+2y=12)
② -x-2y=-12
① x+y=7
② -x-2y=-12
Now putting the equations together,
-y=-5
y=5
x=2
Therefore he bought 2 child tickets and 5 adult tickets
Answer:38
Step-by-step explanation:
N; n+1; n+2 - 3 consecutive numbers
n(n + 1) = (n + 2)² - 19 |use a(b + c) = ab + ac and (a + b)² = a² + 2ab + b²
n² + n = n² + 4n + 4 - 19 |subtract n² from both sides
n = 4n - 15 |subtract 4n from both sides
-3n = -15 |divide both sides by (-3)
n = 5
n + 1 = 5 + 1 = 6
n + 2 = 5 + 2 = 7
Answer: 5; 6; 7.
