how many terms of the sequence 6,10,14.........is to be added to obtain the sum 720?
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a = 6 , d= 4 , n = ?
sn = n/2 {2a + (n-1) d }
720 = n/2 { 12 + 4n - 4 }
1440 = n { 12 + 14n - 4 }
1440 = 12n +14n^2 - 4n
1440 = 8n + 14n^2
14n^2 + 8n - 1440
hope it helps you!!!
sn = n/2 {2a + (n-1) d }
720 = n/2 { 12 + 4n - 4 }
1440 = n { 12 + 14n - 4 }
1440 = 12n +14n^2 - 4n
1440 = 8n + 14n^2
14n^2 + 8n - 1440
hope it helps you!!!
Anonymous:
please do this answer with quatract equation
pleaseeeeeeeeeeeeeeeeeeeeeeee
fastttttttttt
the sum can not be 720
its coming in negative form
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