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If a ≠ 0 and A- 1/A = 3 ; Find : A^3 - 1/A^3 - Mathematics

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प्रश्न

If a ≠ 0 and `a- 1/a` = 3 ; Find :
`a^3 - 1/a^3`

योग

उत्तर

`a- 1/a` = 3...............(Given)

Taking a cube on both sides,

`( a - 1/a )^3 = 3^3`

`a^3 - 1/a^3 - 3( a - 1/a) = 27`..............[(a - b)3 = a3 - b3 -3ab(a - b)]

`a^3 - 1/a^3 - 3 × 3 = 27..............[a- 1/a = 3]`

`a^3 - 1/a^3 - 9 = 27`

`a^3 - 1/a^3` = 27 + 9

`a^3 - 1/a^3` = 36.

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अध्याय 4: Expansions (Including Substitution) - Exercise 4 (B) [पृष्ठ ६०]

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सेलिना Concise Mathematics [English] Class 9 ICSE
अध्याय 4 Expansions (Including Substitution)
Exercise 4 (B) | Q 9.2 | पृष्ठ ६०
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