Question

1st term is 10.Last term is 20.Total number of terms is 5.What is the sum of the terms?

Answer 1

$Heya$‼


$First\:term,a=10$

$Last\:term,a^n=20$

$Number\:of\:terms,n=5$


$As\:we\:know,$
$S^n=\frac{n}{2}[2a+a^n]$

$S^5=\frac{5}{2}[2(10)+20]$

$S^5=\frac{5}{2}(20+20)$

$S^5=\frac{5}{2}*40$

$S^5=5*20$

$S^5=100$


Hence, the sum of the given terms is 100 .