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Find the Square Root of 7 Correct to Two Decimal Places; Then Use It to Find the Value of √ 4 + √ 7 4 − √ 7 Correct to Three Significant Digits. - Mathematics

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Question

Find the square root of 7 correct to two decimal places; then use it to find the value of `sqrt((4+sqrt(7))/(4-sqrt(7)` correct to three significant digits.

Sum

Solution

`sqrt(7)` = 2.645 = 2.65

  2.645
2 7.000000
4
46 300
276
524 2400
2096
5285 30400
26425
  3975 

 

 

 

 

 

 

 

 

 

 

Now, `sqrt((4+sqrt(7))/(4-sqrt(7)`

= `sqrt(((4+sqrt(7))(4+sqrt7))/((4-sqrt7)(4+sqrt(7))`

= `sqrt(((4+sqrt(7))^2)/((4)^2 - sqrt((7))^2)`

= `sqrt(((4+sqrt(7))^2)/(16-7)`

= `sqrt(((4+sqrt(7))^2)/(9)`

= `(4+sqrt(7))/(3)`

= `(4+2.65)/(3)`

= `(6.65)/(3)`

= 2.21

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Chapter 3: Squares and Square Root - Exercise 3 (B) [Page 42]

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Selina Concise Mathematics [English] Class 8 ICSE
Chapter 3 Squares and Square Root
Exercise 3 (B) | Q 7 | Page 42
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