Math, asked by gurvindersingh3960, 11 months ago

Find the value of (4+√15)³ - (4-√15)³ with the help of identity

Answers

Answered by spiderman2019
0

Answer:

128√15

Step-by-step explanation:

use the identity a³ - b³ = (a-b) (a² + ab + b²)

=> a = 4+√15 and b = 4 - √15

ab = (4+√15)(4 - √15) = 16 - 15 = 1

a - b = 4 + √15 - 4 +  √15 = 2√15.

//find out a² + b², by squaring the above equation on  both sides.

(a-b)² = (2√15)²

a²+ b² = 60 + 2ab = 60 + 2 = 62

//Now substitute the values in a³ - b³ = (a-b) (a² + ab + b²)

=> 2√15(62+2)

=> 128√15.

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