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प्रश्न
Which term of the A.P. 7, 13, 19, … is 205?
उत्तर
7, 13, 19, … is 205
Let nth term is 205
Here, a = 7, d = 13 – 7 = 6
205 = a + (n – 1)d
⇒ 205 = 7 + n(n – 1) x 6
⇒ 205 = 7 + 6n – 6
⇒ 6n = 205 –7 + 6 = 204
n = `(204)/(6)` = 34
∴ 205 is 34th term.
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