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a-b-c-d-are-unit-digits-whose-pairwise-sums-form-an-arithmetic-progression-Given-that-a-b-c-d-is-even-find-the-common-positive-difference-of-the-arithmetic-progression-




Question Number 110715 by Aina Samuel Temidayo last updated on 30/Aug/20
a,b,c,d are unit digits whose  pairwise sums form an arithmetic  progression. Given that a+b+c+d is  even, find the common positive  difference of the arithmetic  progression.
a,b,c,dareunitdigitswhosepairwisesumsformanarithmeticprogression.Giventhata+b+c+diseven,findthecommonpositivedifferenceofthearithmeticprogression.
Commented by Rasheed.Sindhi last updated on 30/Aug/20
“pairwise sums of a,b,c,d”  All possible pairs?Order?
pairwisesumsofa,b,c,dAllpossiblepairs?Order?
Commented by Aina Samuel Temidayo last updated on 30/Aug/20
I didn′t change the question. That′s  how it is.
Ididntchangethequestion.Thatshowitis.
Answered by Rasheed.Sindhi last updated on 30/Aug/20
a+b,b+c,c+d are in AP  The common difference:  (b+c)−(a+b)=(c+d)−(b+c)  c−a=d−b  b+c=a+d  −−−−−   1+3=0+4        0,1,3,4         0+1,1+3,3+4  1,4,7  −−−−−  0,2,3,5  0+2,2+3,3+5  2,5,8  −−−−−−  0,2,4,6  0+2,2+4,4+6  2,6,10  −−−−−  1,3,6,8  1+3,3+6,6+8  4,9,14  −−−−−−  1,3,7,9  4,10,16  a,b,c_(−) ,d^(⌢)    a+d=b+c  is only codition for your  question,if I undestand the  question.  a+d=b+c   _(    a+d∈E⇒b+c∈E⇒a+b+c+d∈E)^(•a+d∈O⇒b+c∈O⇒a+b+c+d∈E)       a+b+c+d∈E  −−−−−−−  ^• d=b+c−a    a,b,c,b+c−a     b−a=b+c−a−c     b−a=b−a     ∴ a+b , b+c , c+d is an AP  Generally common difference   is c−a   or  d−b.For making  it positive we will take c>a and  d>b
a+b,b+c,c+dareinAPThecommondifference:(b+c)(a+b)=(c+d)(b+c)ca=dbb+c=a+d1+3=0+40,1,3,40+1,1+3,3+41,4,70,2,3,50+2,2+3,3+52,5,80,2,4,60+2,2+4,4+62,6,101,3,6,81+3,3+6,6+84,9,141,3,7,94,10,16a,b,c,da+d=b+cisonlycoditionforyourquestion,ifIundestandthequestion.a+d=b+ca+dEb+cEa+b+c+dEa+dOb+cOa+b+c+dEa+b+c+dEd=b+caa,b,c,b+caba=b+cacba=baa+b,b+c,c+disanAPGenerallycommondifferenceiscaordb.Formakingitpositivewewilltakec>aandd>b
Commented by Aina Samuel Temidayo last updated on 30/Aug/20
So what is the common difference?
Sowhatisthecommondifference?
Commented by Rasheed.Sindhi last updated on 30/Aug/20
Common difference is not same  for all solutions.Please read last  lines in red color of my solution.
Commondifferenceisnotsameforallsolutions.Pleasereadlastlinesinredcolorofmysolution.
Commented by Aina Samuel Temidayo last updated on 30/Aug/20
With the options I have here, the  common difference is only one.
WiththeoptionsIhavehere,thecommondifferenceisonlyone.

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