GMAT Problem Solving (PS) | Re: In the sequence S, the difference between any two consecutive terms is

Official Solution

•In a sequence S, difference between any two terms is equal


oS is an arithmetic sequence
oLet the first term of the sequence be a and the common difference be d


•4th   term + 5th  term = 7th  term


o4th  term = a + (4-1)*d = a+ 3d
o5th  term = a + (5-1)*d = a +4d
o7th term = a + (7-1)d = a + 6d

•(a + 3d) + (a+4d) = a+6d


o2a + 7d = a + 6d

oa + d = 0

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