Answers

2015-08-27T19:23:06+05:30
In the common difference is equal in the series then the numbers are in A.P
a+d,a+2d,............a+nd.
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2015-08-27T20:30:56+05:30
Sum of first n terms of an A.P. is
     Sn = (n/2)[2a +(n -1)d]1, 3, 5, 79111315, 17, 19, 21, 23 these are ap numbers 
Sum the series 2 +4 +6 +... upto 40 terms.
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