1.

Show that 2+5+8+------+(3n-1)=n(3n+1)/2

Answer»

Nth term = 3n-1

Now to find sum of n terms

Sum = summation tn

sum of n natural numbers = n(n+1)/2

Sum=summation tn

=3(n(n+1)/2 - n

=(3n2+3n-2n)/2

=3n2+n/2

=n(3n+1)/2

hence proved .



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