Prove or disprove that the product of two irrational numbers is irrational.

Emily-Jane Bray

Emily-Jane Bray

Answered question

2021-09-15

Prove or disprove that the product of two irrational numbers is irrational.

Answer & Explanation

doplovif

doplovif

Skilled2021-09-16Added 71 answers

Given statement: The product of two irrational numbers is irrational.
The above statement is not true, thus we need to disprove the statement. A statement is disproven, if we find an example for which the statement is not true.
For example, x=3 is an irrational number and y=33 is another irrational number. We are interest in the product of the two irrational numbers:
xy=333=333=33=1
1 is an integer, thus 1 is not irrational and thus z - y is not an irrational number. We have thus found an example for which the given statement is not true and thus we have disproven the statement.
Results:
Statement is not true for the rational numbers x=3 and y=33
Nick Camelot

Nick Camelot

Skilled2023-05-10Added 164 answers

Step 1
To prove or disprove that the product of two irrational numbers is irrational, we will consider a proof by contradiction.
Assume that x and y are irrational numbers, and we want to determine whether xy is irrational.
We begin by assuming the opposite, that xy is rational. This implies that xy can be expressed as a fraction ab, where a and b are integers and b is not equal to 0.
xy=ab
Step 2
Next, we can rearrange the equation to solve for y:
y=abx
Since x and y are assumed to be irrational, x cannot be equal to 0. Therefore, we can divide both sides of the equation by x:
yx=abx
Simplifying further:
yx=ab
The left-hand side of the equation, yx, represents the division of two irrational numbers, which can also be expressed as a rational number. Let's say yx is equal to cd, where c and d are integers and d is not equal to 0.
yx=cd
Multiplying both sides of the equation by x:
y=cxd
Step 3
Here, we have expressed y as the division of an irrational number (cx) by an integer (d). This means that y can be written as a rational number, which contradicts our initial assumption that y is irrational.
Since our assumption leads to a contradiction, we can conclude that the product of two irrational numbers is indeed irrational.
Therefore, the statement is proven to be true: The product of two irrational numbers is irrational.
Andre BalkonE

Andre BalkonE

Skilled2023-05-10Added 110 answers

To prove or disprove that the product of two irrational numbers is irrational, let's consider a counterexample.
Let x=2 and y=3. Both 2 and 3 are known to be irrational numbers.
Now, let's calculate the product xy:
xy=2·3=6
The value of 6 is also an irrational number. This counterexample demonstrates that the product of two irrational numbers can indeed result in an irrational number.
Therefore, we can conclude that the product of two irrational numbers is irrational, based on the counterexample of x=2 and y=3.
Jazz Frenia

Jazz Frenia

Skilled2023-05-10Added 106 answers

Answer:
x=3 and y=33
Explanation:
To prove or disprove that the product of two irrational numbers is irrational, let's assume we have two irrational numbers, x and y. We need to show that their product, xy, is irrational.
Let's proceed with the proof by contradiction.
Assume that x and y are both irrational numbers, and we want to prove that xy is also irrational.
We can express x as x=3 and y as y=33. (Given in the question)
Now, let's calculate their product:
xy=3·33=(3)23=33=1.
We have obtained xy=1, which is a rational number.
Since xy is rational, our assumption that x and y are both irrational is incorrect.
Therefore, we can conclude that the product of two irrational numbers, x=3 and y=33, is indeed rational.
Hence, we have disproved the statement that the product of two irrational numbers is always irrational.
x=3 and y=33
madeleinejames20

madeleinejames20

Skilled2023-05-27Added 165 answers

To prove or disprove that the product of two irrational numbers is irrational, let's consider the statement:
Statement: The product of two irrational numbers is irrational.
Proof (by contradiction):
Let a and b be two irrational numbers. We assume that their product, ab, is rational.
According to the definition of a rational number, a rational number can be expressed as the quotient of two integers (pq), where q is not equal to zero. Since ab is rational, we can express it as pq, where p and q are integers and q0.
The statement to be proved is written as:
Statement: The product of two irrational numbers is irrational.
We use the proof by contradiction method, so we assume the opposite:
Assumption: Let a and b be two irrational numbers. We assume that their product, ab, is rational.
Now we define a rational number:
Definition: A rational number can be expressed as the quotient of two integers (pq), where q is not equal to zero.
Since we assumed ab to be rational, we can express it as pq, where p and q are integers and q0.
To continue the proof, we will show that this assumption leads to a contradiction.
Continuation of the proof:
Since a and b are both irrational numbers, they cannot be expressed as the quotient of two integers. Therefore, we cannot write a and b as mn and pq, respectively, where m,n,p, and q are integers, and n and q are not equal to zero.
Now, let's consider the product ab. Since a and b are irrational, ab is the product of two numbers that cannot be expressed as the quotient of two integers. Therefore, ab cannot be expressed as pq, which contradicts our assumption.
Hence, our assumption that the product of two irrational numbers is rational leads to a contradiction. Therefore, we can conclude that the product of two irrational numbers is indeed irrational.
Conclusion:
We have proved that the product of two irrational numbers is irrational.

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