Comparison between two power of numbers

In summary, the purpose of comparing two powers of numbers is to determine their relative value or magnitude. This can be done by using a calculator or mathematical rules such as the product and quotient rule. Two powers of different numbers can be compared as long as they have the same base. Comparing powers of numbers is significant in various real-life situations and can help simplify mathematical expressions and equations. However, it has limitations such as only providing a relative comparison and not being applicable for irrational or imaginary numbers.
  • #1
anemone
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Prove that $8^{91}\gt 7^{92}$.
 
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  • #2
anemone said:
Prove that $8^{91}\gt 7^{92}$.

$8^{91} = 7^{91} * ( 1 + \frac{1}{7})^{91}$
$> 7^{91} * ( 1 + \frac{91}{7})$ using for n integer > 1 $(1+x)^n > 1 + nx$ as other terms are positive
$> 7^{91} * 14 > 2* 7^{92} > 7^{92}$
 
  • #3
kaliprasad said:
$8^{91} = 7^{91} * ( 1 + \frac{1}{7})^{91}$
$> 7^{91} * ( 1 + \frac{91}{7})$ using for n integer > 1 $(1+x)^n > 1 + nx$ as other terms are positive
$> 7^{91} * 14 > 2* 7^{92} > 7^{92}$

Very well done, kaliprasad!(Cool)

There is another way to crack the problem, I welcome others to take a stab at it! (Sun)
 
  • #4
kaliprasad said:
$8^{91} = 7^{91} * ( 1 + \frac{1}{7})^{91}$
$> 7^{91} * ( 1 + \frac{91}{7})$ using for n integer > 1 $(1+x)^n > 1 + nx$ as other terms are positive
$> 7^{91} * 14 > 2* 7^{92} > 7^{92}$
it should be:
$8^{91} = 7^{91} * ( 1 + \frac{1}{7})^{91}$
$> 7^{91} * ( 1 + \frac{91}{7})$ using for n integer > 1 $(1+x)^n > 1 + nx$ as other terms are positive
$= 7^{91} * 14 = 2* 7^{92} > 7^{92}$
my solution :using binomial expansion :
$8^{91}=(7+1)^{91}>7^{91}+91(7^{90})=7^{90}(7+91)=7^{90}(7\times7\times 2)=2\times 7^{92}>7^{92}$
 
Last edited:
  • #5
Good job, Albert! (Cool)
 

FAQ: Comparison between two power of numbers

1. What is the purpose of comparing two powers of numbers?

The purpose of comparing two powers of numbers is to determine which number has a greater value or magnitude. This can be helpful in solving mathematical equations or evaluating different quantities.

2. How do you compare two powers of numbers?

To compare two powers of numbers, you can either use a calculator or use mathematical rules such as the product rule and quotient rule. These rules involve multiplying or dividing the numbers being raised to a power and comparing the results.

3. Can two powers of different numbers be compared?

Yes, two powers of different numbers can be compared. However, it is important to note that the two numbers must have the same base in order to be compared. If the bases are different, the powers cannot be directly compared.

4. What is the significance of comparing two powers of numbers?

Comparing two powers of numbers can help in various real-life situations, such as in finance, science, and engineering. It can also aid in simplifying mathematical expressions and solving equations by identifying the larger or smaller value.

5. Are there any limitations to comparing powers of numbers?

One limitation of comparing powers of numbers is that it only gives a relative comparison between the two numbers and does not provide an exact numerical value. Additionally, it is not applicable for comparing irrational or imaginary numbers.

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