Question

(1+1)+(2+2)+(3+3)+.....S17.?

Answer 1

Here,
2+4+6+....T17
So,
a=2
d=4-2=2
We know,
S=n/2[2a+(n-1)d]
Here, n=17
Hence,S=17/2[2×2+(17-1)2]
=306
I hope that it will help you....