CAT Exam Logical Reasoning Number Series

The sum of the first 20 terms of the series -12 + 22 - 32 + 42 - 52 + 62 ... is:

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100

-12+22=10
-32+42=10
-52+62=10
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10 years agoHelpfull: Yes(9) No(0)

22-12=10
42-32=10
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10*10=100
7 years agoHelpfull: Yes(1) No(0)
-12+10x-20 -200-12 = -10
8 years agoHelpfull: Yes(0) No(1)

CAT Other Question

The sum of the first and the 9th of an arithmetic progression is 24. What is the sum of the first nine terms of the progression? Sum of first 25 terms of an AP is 525; sum of the next 25 terms is 725; what is the common difference?