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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता ११ वी

Express the following recurring decimal as a rational number: 2.4¯

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प्रश्न

Express the following recurring decimal as a rational number:

`2.bar(4)`

बेरीज
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उत्तर

`2.bar(4)` = 2 + 0.4 + 0.04 + 0.004 + ...     ...(1)

These terms after the first term form a G.P. whose first term is a = 0.4 and common ratio = r = 0.1

Since |r| = |0.1| = 0.1 < 1, the sum to infinity of this G.P. exists and

S = `"a"/(1 - "r")`

= `0.4/(1 - 0.1)`

= `0.4/0.9`

= `4/9`

∴ from (1), `2.bar(4) = 2 + 4/9 = 22/9`

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पाठ 2: Sequences and Series - Exercise 2.3 [पृष्ठ ३३]

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