Question

if the first term of an ap is 3 and the common difference is 5, then the sum of first 40 terms is​

Answer 1

a= 3

d=5

now sum of first 40 terms

Sn= n/ 2{ 2a+( n- 1) d}

S40=40/2{ 2× 3+( 40-1)5}

S40= 20{6+(39)5}

S40= 20(6+195)

S40= 20(201)

S40= 4020 ans.