# Proof by contradiction

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Is anybody able to help me answer this, I'm completely stuck!

Thanks!

Prove by contradiction that there are no positive integers a and b, with a odd, such that

a + 2b = Root8ab .

Thanks!

Prove by contradiction that there are no positive integers a and b, with a odd, such that

a + 2b = Root8ab .

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Is anybody able to help me answer this, I'm completely stuck!

Thanks!

Prove by contradiction that there are no positive integers a and b, with a odd, such that

a + 2b = Root8ab .

**wills21**)Is anybody able to help me answer this, I'm completely stuck!

Thanks!

Prove by contradiction that there are no positive integers a and b, with a odd, such that

a + 2b = Root8ab .

sqrt(8ab)

or

sqrt(8)ab

Last edited by mqb2766; 1 year ago

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#3

**wills21**)

Is anybody able to help me answer this, I'm completely stuck!

Thanks!

Prove by contradiction that there are no positive integers a and b, with a odd, such that

a + 2b = Root8ab .

Then

Note that a+2b is (odd)+(even) hence it is (odd) and so the square (a+2b)^2 is odd ... but what's the problem ??

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(Original post by

Suppose there there is a pair of integers (a,b), with a odd, such that

Then

Note that a+2b is (odd)+(even) hence it is (odd) and so the square (a+2b)^2 is odd ... but what's the problem ??

**RDKGames**)Suppose there there is a pair of integers (a,b), with a odd, such that

Then

Note that a+2b is (odd)+(even) hence it is (odd) and so the square (a+2b)^2 is odd ... but what's the problem ??

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#6

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that’s the question. simply “prove my contradiction” and it’s 4 marks (edexcel alevel maths)

**wills21**)that’s the question. simply “prove my contradiction” and it’s 4 marks (edexcel alevel maths)

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#8

**wills21**)

Is anybody able to help me answer this, I'm completely stuck!

Thanks!

Prove by contradiction that there are no positive integers a and b, with a odd, such that

a + 2b = Root8ab .

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#9

(Original post by

where can i find this question paper? thanks

**llleahll**)where can i find this question paper? thanks

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#13

(Original post by

any answer to this?

**Hasan167**)any answer to this?

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#16

**RDKGames**)

Suppose there there is a pair of integers (a,b), with a odd, such that

Then

Note that a+2b is (odd)+(even) hence it is (odd) and so the square (a+2b)^2 is odd ... but what's the problem ??

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#17

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But the question doesn’t clarify whether b is odd or even, and if b is also odd then surely the equation can work?

**olliebrown6**)But the question doesn’t clarify whether b is odd or even, and if b is also odd then surely the equation can work?

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#18

**olliebrown6**)

But the question doesn’t clarify whether b is odd or even, and if b is also odd then surely the equation can work?

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#19

**wills21**)

Is anybody able to help me answer this, I'm completely stuck!

Thanks!

Prove by contradiction that there are no positive integers a and b, with a odd, such that

a + 2b = Root8ab .

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#20

**wills21**)

that’s the question. simply “prove my contradiction” and it’s 4 marks (edexcel alevel maths)

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