Question

find no.of terms if sum of A.P 9,17,25....is 636​

Answer 1

Answer:

n =12

Step-by-step explanation:

a=9;d=8:S=636

n/2[2a+(n-1)d]

n/2[2(9)+(n-1)8]

n/2[18+8n-8]

636=n/2=[8n+10]

4n²+5n-636=0

4n²+(53-48)n-636=0

4n²+53n-48n-636=0

4n(n-12)+53(n-12)=0

(n-12) (4n+53)=0

*By Zero Product*

n-12=0

n=12