Proving inequality with mathematical induction

In summary, the conversation is about proving an inequality and seeking tips on how to approach these types of problems. The suggested approach is to start by using the inductive hypothesis and showing that 5k+1+9 < 6(5k+9). The final solution shows that the inequality is true.
  • #1
Instinctlol
79
0
I am having trouble proving these. I cannot figure out how to get to the conclusion. Here is my attempt. The stuff in red is just side work and is not part of the proof. I always get stuck on these types of problems, can someone offer some tips on how to approach these kind of problems in general? Should I start with the right hand side or the left hand side of the inequality?

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  • #2
The goal is to show that 5k+1+9<6k+1. A good place to start is to note that 6k+1 = 6*6k > 6*(5k+9) by the inductive hypothesis like your sidework does. Then it suffices to show that
5k+1+9 < 6(5k+9)
 
  • #3
I think I got it. So,
5k+1 +9 < 6(5k+9)
5*5k + 9 < 6*5k + 54
5*5k < 6 * 5k since 5 < 6
5*5k + 9 < 6 * 5k + 54 since 9<54

Does this look right?
 

FAQ: Proving inequality with mathematical induction

What is mathematical induction?

Mathematical induction is a proof technique used to prove that a statement or formula holds true for all natural numbers. It involves three steps: base case, induction hypothesis, and induction step.

How is mathematical induction used to prove inequalities?

To prove an inequality using mathematical induction, we first establish the base case by showing that the inequality holds true for the smallest possible value. Then, we assume the inequality holds true for a specific value, called the induction hypothesis. Finally, we use this assumption to prove that the inequality holds true for the next value, thus showing that it holds true for all natural numbers.

What are the limitations of using mathematical induction to prove inequalities?

Mathematical induction can only be used to prove inequalities for discrete values, such as natural numbers. It cannot be used to prove inequalities for continuous values, such as real numbers.

Can mathematical induction be used to prove all inequalities?

No, mathematical induction can only be used to prove inequalities that follow a specific pattern or sequence. It cannot be used to prove all types of inequalities.

What are some tips for using mathematical induction to prove inequalities?

Here are some tips to keep in mind when using mathematical induction to prove inequalities:

  • Clearly state the inequality you are trying to prove.
  • Start with the base case and make sure it holds true.
  • Clearly state and use the induction hypothesis in your proof.
  • Be careful to only use the induction hypothesis and not make any additional assumptions.
  • Use a clear and logical approach to prove the inequality for the next value.

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