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Mathematics 18 Online
OpenStudy (anonymous):

The sum of any two consecutive odd numbers is always odd. True or false?

OpenStudy (anonymous):

I know its false but how can i prove it

OpenStudy (anonymous):

False

OpenStudy (midhun.madhu1987):

1+3 = 3+5 = 5+7= try these and u get it

OpenStudy (anonymous):

3+5=8

OpenStudy (anonymous):

i did a few of those and saw its false . Can i prove by contradicting myself?

jimthompson5910 (jim_thompson5910):

Let k be any integer 2k is always even 2k+1 is always odd ------------------------------------------------------- let the first integer be 2k+1 the next integer up is (2k+1) + 2 = 2k+3 ------------------------------------------------------- so the two consecutive even integers is 2k+1 and 2k+3

jimthompson5910 (jim_thompson5910):

add them up: (2k+1)+(2k+3) = 4k + 4 = 2*(k+1) we have something in the form 2*m, where m is an integer and m = k+1 so the sum is always even

jimthompson5910 (jim_thompson5910):

this is also true for any two odd numbers as well (proof is a bit different though, but follows the same basic idea)

OpenStudy (anonymous):

Thank you so much @jim_thompson5910

OpenStudy (anonymous):

ya so if 5+7= 12 then its false for every other problem

OpenStudy (anonymous):

What about if the sum of any three consecutive integers is always divisible by 3. 1+2+3= 6 2+3+4= 9 3+4+5= 12 4+5+6= 15 all these results are divisible by 3.

OpenStudy (anonymous):

@jim_thompson5910 ^

jimthompson5910 (jim_thompson5910):

let x be the first integer x+1 is the next integer after that (x+1)+1 = x+2 is the next one after that

jimthompson5910 (jim_thompson5910):

add them up: (x) + (x+1) + (x+2) x + x+1 + x+2 3x + 3 3*(x+1) so that claim is true because 3 is a factor of 3*(x+1)

OpenStudy (anonymous):

Oh i see it now! That makes more sense!

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