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If X 2 + 1 X 2 = 18 ; Find : X 3 − 1 X 3 - Mathematics

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Question

If `x^2 + (1)/x^2 = 18`; find : `x^3 - (1)/x^3`

Sum

Solution

`(x^3 - (1)/x)^3`

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

⇒ 64 = `x^3 - (1)/x^3 - 3(4)`

⇒ `x^3 - (1)/x^3`
= 64 + 12
= 76.

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Chapter 4: Expansions - Exercise 4.2

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Frank Mathematics [English] Class 9 ICSE
Chapter 4 Expansions
Exercise 4.2 | Q 9.2
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