Question

find value a³+b³-15ab+125 when a+b=-5​

Answer 1

Given

a + b = - 5

Find

a³ + b³ - 15ab + 125

Solution

a + b = - 5

Cube on both sides ;

( a + b )³ = ( - 5 ) ³

a³ + b³ + 3ab ( a + b ) = - 125

a³ + b³ + ( 3a × - 5 ) = - 125

a³ + b³ - 15ab = - 125

a³ + b³ - 15ab + 125 = 0

Hence ,

Answer is 0

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