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!
