Answers

2015-01-23T16:00:22+05:30
REQUIRED SUM=(2+4+6+8+........+30)
(2+4+6+8+.............+2n)=n(n+1)
here, 2n=30
n=30/2=15
15(15+1)=15*16=240

0
2015-01-26T17:42:14+05:30
A= 2
an =30
d=2
n= ( an - a1/d)+1
  (30-2/2)+1=14+1=15
so sum of all even natural numbers between 1 and 31 = n/2(1+1n)=15/2(2+30)
 =15/2 * 32
=240
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