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If X = 1 ( 3 − 2 √ 2 ) and Y = 1 ( 3 + 2 √ 2 ) , Find the Values of X3 + Y3 - Mathematics

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प्रश्न

If x = `(1)/((3 - 2sqrt(2))` and y = `(1)/((3 + 2sqrt(2))`, find the values of 

x3 + y3

योग

उत्तर

x3 + y3

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

Now, x + y = `(1)/((3 - 2sqrt(2))) + (1)/((3 + 2sqrt(2))`

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

= `(6)/(9 - 8)`

= 6

and xy = `(1)/((3 - 2sqrt(2))) xx (1)/((3 + 2sqrt(2))`

= `(1)/(9 - 8)`

= 1

substituting the valuesin (1), we get
(x3 + y3)
= (x + y)3 - 3xy (x + y)
= 216 - 3 x 6
= 198

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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 11.2
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