Deducing Irrational Identity - a1=a2 & b1=b2?

In summary, the equality a1 - √N b1 = a2 - √N b2 can only hold if a1 = a2 and b1 = b2, or if √N is an integer, making N a perfect square. This is because for the equality to hold, the coefficients a - c and d - b must both be integers, which is only possible if a = c and b = d, or if √N is an integer. This problem can be further reduced to proving that √N cannot be rational for square-free N.
  • #1
basil
8
0
How do you deduce that

a1 - [itex]\sqrt{N}[/itex] b1 = a2 - [itex]\sqrt{N}[/itex]b2

to be

a1=a2 and b1=b2?
 
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  • #2
Matching coefficients?
 
  • #3
You can't: Take N = 4, a1=5, b1=1, a2=15, and b2=6
 
  • #4
daveb said:
You can't: Take N = 4, a1=5, b1=1, a2=15, and b2=6

In this case, they are only equal because N is a perfect square.

If a + b√N = c + d√N, then
a - c = (d - b)√N

Assuming a, b, c, d are integers, then (a - c) is an integer, thus for equality, (d - b)√N must be an integer. This is only true if a = c and b = d, or if √N is an integer, making N a perfect square.
 
Last edited:
  • #5
Hey guys,

I see now...Thanks! Appreciate it.
 
  • #6
Unit said:
Assuming a, b, c, d are integers, then (a - c) is an integer, thus for equality, (d - b)√N must be an integer. This is only true if a = c and b = d, or if √N is an integer, making N a perfect square.

You skipped a step. sqrt(N) could have been rational, with (d-b) divisible by the denominator. And so this problem is reduced to proving that sqrt(N) cannot be rational for square-free N.
 

1. What is meant by "Deducing Irrational Identity"?

Deducing irrational identity refers to the process of finding a relationship between two irrational numbers, such as a1 and a2, and b1 and b2. This relationship can be expressed as a mathematical equation, such as a1=a2 and b1=b2.

2. Can irrational identity be proven?

No, irrational identity cannot be definitively proven. This is because irrational numbers, by definition, cannot be expressed as a ratio of two integers. Therefore, there is no way to prove that two irrational numbers are equal. However, we can use deductive reasoning and mathematical equations to show that they are equivalent.

3. How is irrational identity different from rational identity?

Irrational identity refers to the relationship between two irrational numbers, while rational identity refers to the relationship between two rational numbers. Rational numbers can be expressed as a ratio of two integers, but irrational numbers cannot. Therefore, the methods used to prove or deduce their identities are different.

4. Why is irrational identity important in mathematics?

Irrational identity is important in mathematics because it allows us to understand and work with irrational numbers, which play a crucial role in many mathematical concepts such as geometry, calculus, and number theory. It also helps us to better understand the nature of numbers and their relationships, leading to new discoveries and advancements in mathematics.

5. What are some real-life applications of irrational identity?

Irrational identity has many real-life applications, such as in measuring lengths and distances, calculating areas and volumes, and in various fields of science and engineering. For example, the ratio of a circle's circumference to its diameter, also known as pi (π), is an irrational number. This means that irrational identity is used in various calculations involving circles, such as in the design of wheels, gears, and other circular objects.

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