. How many terms of the AP. 2, 4, 6, 8, 10,... are needed to get sum 2

1.	. How many terms of the AP. 2, 4, 6, 8, 10,... are needed to get sum 210 ?
Answer» 2,4,6,8,10,.... a = 2 d = 4 - 2 = 2 Sn = 210 Sn = n/2(2a+(n-1)d) 210 = n/2(2×2+(n-1)2) 210 = n(2+n-1) 210 = nn + n nn + n - 210 = 0 (n+15)(n-14) = 0 n = 14 14 terms required. If you find this answer helpful then like it.

. How many terms of the AP. 2, 4, 6, 8, 10,... are needed to get sum 210 ?

Answer»

2,4,6,8,10,.... a = 2 d = 4 - 2 = 2 Sn = 210 Sn = n/2(2a+(n-1)d) 210 = n/2(2×2+(n-1)2) 210 = n(2+n-1) 210 = n*n + n n*n + n - 210 = 0 (n+15)(n-14) = 0 n = 14 14 terms required.

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. How many terms of the AP. 2, 4, 6, 8, 10,... are needed to get sum 210 ?

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