if 9th of an Arthemthic progression is 0, prove that its 29th term is double the 19th term
if 9th of an Arthemthic progression is 0, prove that its 29th term is double the 19th term
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Concept used :
nth term of an AP = a + (n-1)d
Step-by-step explanation:
Given,
9th term = 0
=> a + 8d = 0
=> a = -8d ----------(1)
Now,
29th term = a + 28d= -8d + 28d = 20d
(from eq 1 )
29th term = 20d --------(2)
19th term = a + 18d = -8d + 18d = 10d
(from eq 1 )
19th term = 10d --------(3)
from (2) and (3)
29th term = 2 x 19th term
hence proved