Question

if an is equal to 5n -2 then find sn​

Answer 1

Answer:

an = 5n-2

so a1 = 5(1)-2=5-2=3

a2= 5(2)-2=10-2=8

sa a= 3 , d = 8 - 3 =5

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

= n/2[ 2(3) + (n-1)5]

= n/2[ 6+5n-5]

= n/2[ 5n+1 ]

= 5n²+n/2

Step-by-step explanation:

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