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
