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Mathematics

Find the 30th term of the sequence :

12,1,32,.........\dfrac{1}{2}, 1, \dfrac{3}{2}, ………

AP

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Answer

Since, 112=12,321=121 - \dfrac{1}{2} = \dfrac{1}{2}, \dfrac{3}{2} - 1 = \dfrac{1}{2}.

Hence, the series is an A.P. with common difference = 12\dfrac{1}{2}.

We know that nth term of an A.P. is given by,

⇒ an = a + (n - 1)d, where a is the first term.

So, 30th term is,

a30=12+(301)×12=12+292=302=15.\Rightarrow a_{30} = \dfrac{1}{2} + (30 - 1) \times \dfrac{1}{2} \\[1em] = \dfrac{1}{2} + \dfrac{29}{2} \\[1em] = \dfrac{30}{2} \\[1em] = 15.

Hence, 30th term of the sequence = 15.

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