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Why is sqrt 2 irrational?

Updated: 11/2/2022
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14y ago

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First we will assume that sqrt(2) is rational, meaning that it can be written as a ratio of two integers say (p/q) p and q must have no common factors sqrt(2)=p/q, square both sides 2=p^2/q^2, multiply both sides by q^2 2q^2=p^2, since 2 divides by the LHS, so does the RHS, meaning that p^2 is evenand because p^2 is even, so is p itselfLet p=2r with r being an integer so that p^2=2q^2=(2r)^2=4r^ 2Since 2q^2=4r^2, q^2=2r^2Because q^2 is 2r^2, then q^2 is even, meaning q itself is evenSince p and q are even, they have a common factor of 2THEREFORE, sqrt(2) cannot be rational

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Q: Why is sqrt 2 irrational?
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Is an irrational number closed under division?

No. sqrt(8) is irrational sqrt(2) is irrational but sqrt(8) /sqtr(2) = sqrt(4) = ±2 is not irrational.;


Can you add two positive irrational numbers to get an irrational number?

Yes. sqrt(2) + sqrt(2) = 2*sqrt(2), an irrational number.


How can be the product of 2 irrational numbers a rational numbers 5?

5*sqrt(2) is one irrational number. 1/sqrt(2) is another irrational number.Their product is 5!5*sqrt(2) is one irrational number. 1/sqrt(2) is another irrational number.Their product is 5!5*sqrt(2) is one irrational number. 1/sqrt(2) is another irrational number.Their product is 5!5*sqrt(2) is one irrational number. 1/sqrt(2) is another irrational number.Their product is 5!


Is a rational number times a irrational number?

Can be irrational or rational.1 [rational] * sqrt(2) [irrational] = sqrt(2) [irrational]0 [rational] * sqrt(2) [irrational] = 0 [rational]


Is the sum of irrational roots irrational?

Not always. For example: sqrt(2)+(-sqrt(2))=0 which is not irrational.


If you divide 2 irrational numbers is the answer always an irrational number?

No, not always. For example, sqrt(2) is irrational (1.41421...), but sqrt(2)/sqrt(2) = 1. 1 is a rational number. Similarly, 2*sqrt(2) is irrational (2.82842...), but sqrt(2)/(2*sqrt(2)) = 1/2. 1/2 is a rational number.


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Yes, but not always. An easy example is sqrt(2)*sqrt(3), which is sqrt(6) and irrational. An easy counterexample is simply sqrt(2) * sqrt(2), which is 2 and rational.


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Yes. Sqrt(8) and sqrt(2) are both irrational. sqrt(8)/sqrt(2) = sqrt(8/2) = sqrt(4) = 2 is rational.