problem 639

Sir SagarMarch 18, 2015March 18, 20150

Find S10 for 2 + 5 + 8 +…

Solution:-

We know S = $\frac{n}{2}[2a_{1}+(n-1)d]$ , Where a1 = first term , n = finding term , d = second term – first term.

S10 = $\frac{10}{2}[2*2_{1}+(10-1)3]$

S10 = 155

So the value of S10 155.

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