Answer:
A
Step-by-step explanation:
9 = (1/27)^(a+3)
3² = (3^-3)^(a+3)
3² = 3^(-3a-9)
2 = -3a-9
-3a = 11
a = -11/3
There is nothing attached
Answer:
x=20
Step-by-step explanation:
Please mark as brainliest
Answer:
-33 or 33
Step-by-step explanation:
The seventh term of an AP is written as:
![a + 6d](https://tex.z-dn.net/?f=a%20%2B%206d)
The eleventh term of an AP is written as:
![a + 10d](https://tex.z-dn.net/?f=a%20%2B%2010d)
If the 7th term is 11 times the 11th term, then;
![a + 6d = 11(a + 10d)](https://tex.z-dn.net/?f=a%20%2B%206d%20%3D%2011%28a%20%2B%2010d%29)
Expand to get:
![a + 6d = 11a + 110d](https://tex.z-dn.net/?f=a%20%2B%206d%20%3D%2011a%20%2B%20110d)
![11a - a = 6d - 110d](https://tex.z-dn.net/?f=11a%20-%20a%20%3D%206d%20-%20110d)
![10a = - 104d](https://tex.z-dn.net/?f=10a%20%3D%20%20-%20104d)
![\frac{a}{d} = - \frac{104}{10}](https://tex.z-dn.net/?f=%20%5Cfrac%7Ba%7D%7Bd%7D%20%20%3D%20-%20%20%20%5Cfrac%7B104%7D%7B10%7D%20)
![\frac{a}{d} = - \frac{52}{5}](https://tex.z-dn.net/?f=%20%5Cfrac%7Ba%7D%7Bd%7D%20%20%3D%20-%20%20%20%5Cfrac%7B52%7D%7B5%7D%20)
We must have a=-52 and d=5
Or
a=52 and d=-5
For the first case, the 18th term is :
![- 52 + 5 \times 17 = 33](https://tex.z-dn.net/?f=%20-%2052%20%2B%205%20%5Ctimes%2017%20%3D%2033)
For the second case,
![52 - 5 \times17 = - 33](https://tex.z-dn.net/?f=52%20-%205%20%5Ctimes17%20%3D%20%20-%2033)