Question

answer question 24 please quickly very important

Answer 1

★ Hi , there !!★


given => x = 9 + 4 √ 5



xy = 1

or ,


x = 1 / y


or , y = 1 / x



now ,



1 / x = 1 / 9 + 4 √ 5 × 9 -4√ 5 / 9 - 4 √ 5


1 / x = 9 - 4 √ 5 / 81 - 80


1 / x = 9 -4√ 5 -------------------(1)


now ,




1/ x² + 1 / y² => x² + y² /( xy)²


{ 1/ y² = x ² }


=> ( 9 + 4√ 5 ) ² + ( 9 - 4 √ 5 )² / ( 1 )²


=> 81 + 80 + 8 √ 5 + 81 + 80 - 8 √ 5


=> 81 + 81 + 80+ 80


=> 322




hope it helps you dear friend !!


thanks !!

Answer 2

hey there ,,, how's going on !!,

.. x = 9 + 4√5 ∴ y = 1/x = 9 - 4√5 

∴ x + y = 18 ... and ... xy = 1 ............... (1)
__________________________ 

∴ (1/x²) + (1/y²) 

= ( x² + y² ) / (x²y²) 

= [ (x+y)² - 2(xy) ] / (xy)² 

= [ (18)² - 2(1) ] / (1)² ............. from (1) 

= ( 324 - 2 ) / (1) 

= 322 ..........................

hope that must help

himanshu Jha