find the sum if the first 20 terms of the arithmetic sequence 8,14,20........
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Answered by
3
Answer:
Hi!!!
a = 8
d = (14-8) = 6
n=20
S = n/2(a + (n-1)d)
S = 20/2(8 + (20-1)6)
S = 10(8 + (19)6)
S = 10(8 + 114)
S = 10(122)
S = 1220.
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Answered by
3
Step-by-step explanation:
Arithmetic sequence = 8, 14, 20......
= 8, (8+6), (8+2*6).......
its in Ap form a, (a+d), (a + 2d )
d = a2- a1 = 14- 8 = 6
d= 6
a= 8
*** Sn = n/2 [2a +( n-1)d]
S20 = 20/2 [ 2*8 +(20-1)6]
S20 = 10 [ 16 + (19) 6]
S20 = 10 [ 16 + 114 ]
S20 = 10 [130]
S20 = 1,300
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