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Evaluate, correct to one place of decimal, the expression 520-10, if 5 = 2.2 and 10 = 3.2. - Mathematics

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Question

Evaluate, correct to one place of decimal, the expression `5/(sqrt20 - sqrt10)`, if `sqrt5` = 2.2 and `sqrt10` = 3.2.

Sum

Solution

Given - `sqrt5` = 2.2 and `sqrt10` = 3.2.

`5/(sqrt20 - sqrt10)`

`= 5/(sqrt20 - sqrt10) xx (sqrt20 + sqrt10)/(sqrt20 + sqrt10)`

`= (5 (sqrt(20) + sqrt10))/(20 - 10)`

`= (cancel(5)^1 (sqrt(20) + sqrt10))/(cancel(10)_2)`

`= (sqrt(20) + sqrt10)/2`

`= (sqrt(4 xx 5) + sqrt10)/2`

`= (2sqrt5 + sqrt10)/2`

`= (2(2.2) + 3.2)/2`

`= (4.4 + 3.2)/2`

`= 7.6/2`

= 3.8

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Simplifying an Expression by Rationalization of the Denominator
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Chapter 1: Rational and Irrational Numbers - Exercise 1 (D) [Page 22]

APPEARS IN

Selina Concise Mathematics [English] Class 9 ICSE
Chapter 1 Rational and Irrational Numbers
Exercise 1 (D) | Q 3. | Page 22
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