Is a(n) bounded by a(1)*c^(n-1)?

  • Thread starter transgalactic
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    Proof
For the induction step, assume the inequality is true for n=k. Then, for n=k+1, we have a(k+1)<=c*a(k) <= c*a(1)*c^(k-1) = a(1)*c^k. Therefore, by induction, the inequality holds for all positive integers n. In summary, the given sequence satisfies the inequality a(n)<=a(1)*c^(n-1) for all positive integers n.
  • #1
transgalactic
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i am given a real and positive number a1 a2 a3 ...
which goes by a(n)<=c*a(n-1) for every n=>2 for a certain given number c>0 .

prove that
a(n)<=a(1)*c^(n-1)

??

a(n) is the n'th number of the series
 
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  • #2
Use a proof by induction. It should be fairly straight forward.
 
  • #3
i don't have a base case here

and there are two variables

??
 
  • #4
Use induction of n. Your base case would be n=2.
 
  • #5
for n=2
i get
a(2)=c*a(1)

this base case doesn't prove anything

??
 
  • #6
The base case is trivially true, since it is the same condition for the members of the sequence.
 

1. What does it mean for a function to be bounded by a constant raised to the power of n-1?

When a function is bounded by a constant raised to the power of n-1, it means that as the value of n increases, the function's growth is limited by the value of the constant. In other words, the function will never exceed or fall below the value of the constant multiplied by the value of n-1.

2. How do you determine if a function is bounded by a constant raised to the power of n-1?

To determine if a function is bounded by a constant raised to the power of n-1, you can graph the function and observe its behavior as n increases. If the function stays within a certain range, it is likely bounded by the constant. You can also use mathematical techniques such as limits or Big O notation to analyze the function's growth rate.

3. Can a function be bounded by a constant raised to a negative power?

Yes, a function can be bounded by a constant raised to a negative power. In this case, the function's growth will be limited as n decreases. This can be useful in certain applications, such as when analyzing the time complexity of algorithms with decreasing input sizes.

4. What are some examples of functions that are bounded by a constant raised to the power of n-1?

Some examples of functions that are bounded by a constant raised to the power of n-1 include logarithmic functions (such as log n), polynomial functions (such as n^2), and exponential functions (such as e^n). These functions all have growth rates that are limited by a constant as n increases.

5. How does a function being bounded by a constant raised to the power of n-1 relate to its time complexity?

When a function is bounded by a constant raised to the power of n-1, it means that its growth rate is limited by a constant as the input size increases. In terms of time complexity, this means that the function has a polynomial time complexity, which is considered to be efficient. Functions that are not bounded in this way may have exponential or factorial time complexity, which can quickly become inefficient as the input size increases.

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