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!
The greatest whole number that rounds to 7,400 would be 7,399. This is because there is no number that is larger than 7,399 that would round up to 7,400, since 7,400 is the next number.
The least whole number that rounds to 7,400 would be 7,401. This is because there is no number that is less than 7,401 that would round up to 7,400, since 7,400 is the next number.
Givens
Petri Dish A sees a double ever 10 minutes
Petri Dish B sees a double ever 6 minutes
Consequences
A doubles 60 / 10 = 6 times.
B doubles 60 / 6 = 10 times.
Solution
If you work best with numbers then suppose there are 100 bacteria in both dishes at the beginning
A = 100 * 2^6
B = 100 * 2^10
A will have 100 * 64 = 6400 bacteria growing inside A
B will have 100 * 1024 = 102400 bacteria growing inside B
B/A = 102400 / 6400 = 16
There are 16 times as many in B than in A. <<<< Answer
