Question

If a+b=8 and ab=6 then find the value of a^3 +b^3

Answer 1

(a + b) = 8



Cube on both sides,

(a + b)³ = 8²

a³ + b³ + 3ab(a + b) = 8³

a³ + b³ + 3(6)(8) = 512

a³ + b³ + 144 = 512

a³ + b³ = 512 - 144

a³ + b³ = 368


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Answer 2

Hey !!!

given :- a + b = 8
ab = 6

a³ + b³ = ( a + b ) ( a² + b² - ab )

=> {( a + b ) (a + b ) ²- 2ab - ab }

=> { (a + b ) ( a + b)²- 3ab ) }

=> 8 { ( 8)²- 3 × 6}

=> 8 { 64 - 18 }

=> 8 × 46

=> 368 Answer ✔

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Hope it helps you !!!

@Rajukumar111