Question

how many terms of the AP: 36, 33, 30....... must be taken so that their sum is 126​

Answer 1

Answer:

7 term will take to make the sum of 126

Step-by-step explanation:

this will help you

Answer 2

Answer:

4th, 21th term is the answer

Step-by-step explanation:

a=36

d=33-36=-3

Sn=126

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

126=n/2{2×36+(n-1)-3}

252=n{72-3n+3}

252=n(75-3n)

252=75n-3n²

n²-25n+84=0

n²-21n-4n+84=0

n(n-21) -4(n-21) =0

(n-4) (n-21) =0

n=4,21

taking n=21

Sn=21/2(72-60)

= 21×12/2

→ = 126

taking n=4

Sn=4/2(72-9)

=2(63)

→ =126

→so we will take n=4 , 21←

\\I hope it was helpful..//:)