Question

Part 1!

Answer 1

1.  We have to find the fifth term of f(n) = 7 - 4(n - 1). 
That means x = 5. Substitute 5 into the equation for x. 
f(n) = 7 - 4(5 - 1) 
Subtract 5 - 1. 
f(n) = 7 - 4(4) 
Multiply 4 by 4. 
f(n) = 7 - 16 
Subtract 16 from 7. 
f(n) = -9 
The answer is D. 

2. Since we have to find the first 4 terms, we have to solve for x = 1, 2, 3, & 4. 
Multiply 1, 2, 3, and 4 by 6. We now have: 
f(x) = 6 - 25   f(x) = 12 - 25   f(x) = 18 - 25   f(x) = 24 - 25 
Subtract 25 from the first term: 6, 12, 18, and 24. 
f(x) = -19   f(x) = -13   f(x) = -7   f(x) = -1 
The answer is C. 

3. Now, we have to find the first 3 terms of f(x) = 10(2)^x.  So x is 1, 2, & 3. 
Raise 2 to the powers of 1, 2, and 3. The equations are now: 
f(x) = 10(2)   f(x) = 10(4)   f(x) = 10(8) 
Then multiply 10 by the three terms: 2, 4, and 8. 
f(x) = 20   f(x) = 40   f(x) = 80 
The answer is A. 

4. Find the 21st term of f(n) = 2 + 9(n - 1). Substitute 21 for n. 
f(n) = 2 + 9(21 - 1) 
Subtract 1 from 21. 
f(n) = 2 + 9(20) 
Multiply 9 by 20. 
f(n) = 2 + 180
Add 2 to 180. 
f(n) = 182 
The answer is B. 

5. Which sequence is described by f(n) = 2(3)^x-5. 
This is the only one which I'm not sure how to solve. Since I don't know, I won't answer it because I don't want to give you the wrong answer to the question, sorry about that. 

6. The ninth term in f(n) = 384(1/2)^n-1. Put 9 in for n & subtract 1 from 9. 
f(n) = 384(1/2)^8 
Raise 1/2 to the power of 8.
f(n) = 384(1/256) 
Multiply 1/256 by 384. 
f(n) = 384/256 
Reduce the fraction & make it a mixed number. 
f(n) = 1 1/2 

Hope this helped!