हिंदी

If X = ( 2 + √ 5 ) ( 2 − √ 5 ) and Y = ( 2 − √ 5 ) ( 2 + √ 5 ) , Show that (X2 - Y2) = 144 √ 5 . - Mathematics

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प्रश्न

If x = `((2 + sqrt(5)))/((2 - sqrt(5))` and y = `((2 - sqrt(5)))/((2 + sqrt(5))`, show that (x2 - y2) = `144sqrt(5)`.

योग

उत्तर

x = `((2 + sqrt(5)))/((2 - sqrt(5))` 

= `((2 + sqrt(5)))/((2 - sqrt(5))) xx ((2 + sqrt(5)))/((2 + sqrt(5))`

= `(2 + sqrt(5))^2/(4 - 5)`

= `-(4 + 5 + 4sqrt(5))`

= `-9 -4sqrt(5)`

y = `((2 - sqrt(5)))/((2 + sqrt(5))`

= `((2 - sqrt(5)))/((2 + sqrt(5))) xx ((2 - sqrt(5)))/((2 - sqrt(5))`

= `(2 - sqrt(5))^2/(4 - 5)`

= `-(4 + 5 -4sqrt(5))`
= `-9 + 4sqrt(5)`
∴ x2 - y2  = (x + y) (x - y)
= `(-9 - 4sqrt(5) - 9 + 4sqrt(5))(-9 -4sqrt(5) + 9 - 4sqrt(5))`
= `(-18)(-8sqrt(5))`
= `144sqrt(5)`

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Simplifying an Expression by Rationalization of the Denominator
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 1: Irrational Numbers - Exercise 1.3

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फ्रैंक Mathematics [English] Class 9 ICSE
अध्याय 1 Irrational Numbers
Exercise 1.3 | Q 9
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