Question

if a+b =12 and ab=27,find the value of a³+b³

Answer 1

Hey !!!

a + b = 12 |given|
ab = 27

•°• we know that

a³ + b ³ = (a + b ) ( a² + b² - ab )

and , ( a + b ) ²- 2ab = a² + b²

so , a³ + b³= ( a + b ){ ( a + b )² - 3ab }

hence , a³ + b³ = 12{12²- 3 ×27 } ✔ putting the given value

=> 12 { 144- 3×27 }

=> 12×63

= > 756 Answer

a³ + b³ = 756 Answer

___________________

Hope it helps you !!

#Rajukumar111

Answer 2

Answer :

Now,

a³ + b³

= (a + b)³ - 3ab(a + b)

= 12³ - (3 × 27 × 12) [∵ a + b = 12, ab = 27]

= 1728 - 972

= 756

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