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Evaluate: (√50 + √42)^1/3 ⁢(√50 − √42)^1/3 - Mathematics

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Question

Evaluate:

`(sqrt(50) + sqrt(42))^(1/3) (sqrt(50) - sqrt(42))^(1/3)`

Evaluate
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Solution

Given,

`(sqrt(50) + sqrt(42))^(1/3) (sqrt(50) - sqrt(42))^(1/3)`

We have to evaluate the given terms.

Thus, `(sqrt(50) + sqrt(42))^(1/3) (sqrt(50) - sqrt(42))^(1/3)`

⇒ `[(sqrt(50) + sqrt(42)) (sqrt(50) - sqrt(42))]^(1/3)`  ...[∴ an × bn = abn]

⇒ `[(sqrt(50))^2 - (sqrt(42))^2]^(1/3)`  ...[∴ (a + b)(a – b) = a2 – b2]

⇒ `[50 - 42]^(1/3)`

⇒ `[8]^(1/3)`

⇒ `[2^3]^(1/3) = 2^(3 xx 1/3)`

⇒ 2

Hence, `(sqrt(50) + sqrt(42))^(1/3) (sqrt(50) - sqrt(42))^(1/3) = 2`

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Chapter 6: Indices - EXERCISE 6 [Page 66]

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B Nirmala Shastry Mathematics [English] Class 9 ICSE
Chapter 6 Indices
EXERCISE 6 | Q 4. (i) | Page 66
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