Question

if a=2 ,r=3 ,Sn=242 find n​

Answer 1

Step-by-step explanation:

here,

a=2 , d=3 , Sn=242

Sn=n÷2{2a+(n-1)d}

242=n÷2{2×2+(n-1)3}

484=n{4+3n-3}

484=n{1+3n}

484=1n+3n2

484=1n +3n×n

484=4n×n

n2=484÷2

n2=242

n=√242

n=11√2

Answer 2

Answer:

n=5

Step-by-step explanation:

a=2 r=3 Sn=242 n=?

Sn=a(1-r)/(1-r)

242=2(1-3^n)/(1-3)

242=-(1-3^n)

242=-1+3^n

243=3^n

3^5=3^n

therefore n=5