Question

a)1+2+3+..................+150=? b)4+8+12+......................+84=?​

Answer 1

Step-by-step explanation:

First we have to find the nth term. ..

a+(n-1)d = 150

=> 1 + (n - 1)(1) = 150

=>n = 150 ...

so the sum of nth term...

sum = n/2 [ a + l ] ( l = last term of AP)

sum = 150/2 [1+ 150]

sum = 75 × 151

sum = 11325....

so if we will divide it by 15...

= 11325 / 15

=755...