Question

Determine a soma dos 10 primeiros ermos da P.A.que tem a1=1 e r=1

Answer 1

Sn= $\frac{(a1+an) x n}{2}$

Sn= $\frac{(1+10)x10}{2}$

Sn= $\frac{11x10}{2}$

Sn= $\frac{110}{2}$

Sn= 55