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If X = ( √ 3 + 1 ) ( √ 3 − 1 ) and Y = ( √ 3 − 1 ) ( √ 3 + 1 ) , Find the Values of X3 + Y3 - Mathematics

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प्रश्न

If x = `((sqrt(3) + 1))/((sqrt(3) - 1)` and y = `((sqrt(3) - 1))/((sqrt(3) + 1)`, find the values of 

x3 + y3

योग

उत्तर

x3 + y3

x3 + y3 = (x + y)3 - 3xy(x + y)  ----(1)

∴ (x + y) = `((sqrt(3) + 1))/((sqrt(3) - 1)) + ((sqrt(3) - 1))/((sqrt(3) + 1)`

= `((sqrt(3) + 1)^2 + (sqrt(3) - 1)^2)/(3 - 1)`

= `(3 + 1 + 2sqrt(3) + 3 + 1 - 2sqrt(3))/(2)`

= `(8)/(2)`

= 4

and xy = `((sqrt(3) + 1))/((sqrt(3) - 1)) xx ((sqrt(3) - 1))/((sqrt(3) + 1)`

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

= 1

substitutingin (1), we get
x3 + y3
= (x + y)3 - 3xy(x + y)
= 64 - 3 x 4
= 64 - 12
= 52

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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 10.2
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