Find n if the given value of x is the nth term of the given A.P.
(i)
(ii)
(iii)
(iv)
(i)
a = 25, d = 50 – 25 = 25
Last term, l = 1000
Number of terms, n = 
+ 1
= 
+ 1 = 40
Hence, the value of n is 40
(ii)
a = -1, d = -2
Last term, l = -151
Number of terms, n = 
+ 1
= 
+ 1 = 76
Hence, the value of n is 76
(iii)
a = 
, d = 
Last term, l = 550
l = a + (n – 1) d
550 = 
+ (n – 1) 
550 = 
1100 = 11n
n = 100
Hence, number of terms, n = 100
(iv)
a = 1, d = 
– 1 = 
Last term, l = 
a + (n – 1) d = 
1 + (n – 1) 
=
= 
– 1 + 
= 
10n = 170
n = 17
Hence, value of n is 17
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