Question

In
an
AP given, a=2, d=8
Sn=9, find n and an​

Answer 1

Step-by-step explanation:

sn should be 90

plz check it

Answer 2

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

$9=n/2[4+(n-1)8]$

$18=4n+8n^2-8n$

$18=8n^2-4n$

$18=4n(2n-1)$

$18+4n÷4n=2n$

18=8n-4n

18=4n

n=18/4✏️✏️✏️✏️✏️

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