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#1
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 .
0
1 year ago
#2
(Original post by 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 .
Is that
sqrt(8ab)
or
sqrt(8)ab
Last edited by mqb2766; 1 year ago
0
1 year ago
#3
(Original post by 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 .
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 ??
1
#4
(Original post by mqb2766)
Is that
sqrt(8ab)
or
sqrt(8)ab
(8ab)
0
#5
(Original post by 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 ??
that’s the question. simply “prove my contradiction” and it’s 4 marks (edexcel alevel maths)
0
1 year ago
#6
(Original post by wills21)
that’s the question. simply “prove my contradiction” and it’s 4 marks (edexcel alevel maths)
Yes they've given you a big hint, they're asking you what the problem is (i.e. can you spot the contradiction now?)
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1 year ago
#7
Ahh just spotted it
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1 month ago
#8
(Original post by 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 .
where can i find this question paper? thanks
0
1 month ago
#9
(Original post by llleahll)
where can i find this question paper? thanks
is it aqa or edexcel?
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1 month ago
#10
anyone know what paper this question is from?
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1 month ago
#11
I think it is the Edexcel 2020 mock paper set 2 but only teachers can access it.
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1 month ago
#12
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1 month ago
#13
(Original post by Hasan167)
Do you mean the original question? That was answered a year ago in post #3
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1 month ago
#14
Bb
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1 month ago
#15
Look at all the people here trying to cheat, loooooollllll
2
1 month ago
#16
(Original post by 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 ??
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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1 month ago
#17
(Original post by 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?
Trying out a few numbers may be useful?
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1 month ago
#18
(Original post by 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?
Yes but it doesnt matter what b is, as it is 2b it is a multiple of 2 and a multiple of two always even e.g if b is 3 2b is 6 which is even etc
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1 month ago
#19
(Original post by 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 .
By any chance do you remember what question paper this is from
0
1 month ago
#20
(Original post by wills21)
that’s the question. simply “prove my contradiction” and it’s 4 marks (edexcel alevel maths)
Do you know the specific paper??
0
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