मराठी

The value of [1–2 + 2–2 + 3–2 ] × 62 is ______. - Mathematics

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प्रश्न

The value of [1–2 + 2–2  + 3–2 ] × 62 is ______.

रिकाम्या जागा भरा

उत्तर

The value of [1–2 + 2–2  + 3–2 ] × 62 is 49.

Explanation:

Using law of exponents, `a^-m = 1/a^m`  ...[∵ a is non-zero integer]

∴ `[1^-2 + 2^-2 + 3^-2] xx 6^2 = [1/1^2 + 1/2^2 + 1/3^2] xx 6^2`

= `[1 + 1/4 + 1/9] xx 6^2`

= `((36 + 9 + 4)/36) xx 6^2`

= `(49/36) xx 6^2`

= `(7/6)^2 xx 6^2`

= (7)2 × 6–2 × 62

= (7)2 × 62 – 2

= (7)2 × 60  ...[a0 – 1]

 = 49  

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पाठ 8: Exponents and Powers - Exercise [पृष्ठ २५५]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 8
पाठ 8 Exponents and Powers
Exercise | Q 65. | पृष्ठ २५५

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