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प्रश्न
Find the 19th term of the following A.P.:
7, 13, 19, 25, ...
उत्तर
The sequence given is 7, 13, 19, 25, ....
Here,
First term = a = t1 = 7, t2 = 13, t3 = 19, t4 = 25, ....
Common difference = d = t2 − t1
= 13 – 7
= 6
To find the 19th term, we have to use the formula, i.e.,
tn = a + (n − 1)d
∴ t19 = 7 + (19 − 1) × 6 ...(On substituting value)
∴ t19 = 7 + 18 × 6
∴ t19 = 7 + 108
∴ t19 = 115
Hence, the 19th term of the progression is 115.
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