`Sigma_(n=1)^(13)(i^(n)+i^(n+1))`का मान ज्ञात कीजिए |

Answer

i-1

Explanation

`underset(n=1)overset(13)Sigma (i^(n)+i^(n+1))=i+i^(2)+i^(3)+…+i^(13)+i^(14)`
`=i+2[i^(2)+i^(3)…i^(13)]-1=i+2[(i^(2)(1-i^(12)))/(1-i)]-1`
`=i+2[(-1(1-(i^(2))^(6)))/(1-i)]-1=i-1`