Question

if X + Y is equal to 4 then the value of x cube + y cube + 2 X Y is equal to​

Answer 1

x cube + y cube + 2XY = 64-10XY is the correct

answer

Answer 2

Answer:

$x + y = 4 \\ cube \: both \: side \: we \: get \\ {(x + y)}^{3} = 4 {}^{3} \\ {x}^{3} + {y}^{3} + 3xy(x + y) = 64 \\ {x}^{3} + {y}^{3} + 3xy(4) = 64 \\ {x}^{3} + {y}^{3} + 12xy = 64 \\ subtract \: 10xy \: from \: both \: side \\ {x}^{3} + {y}^{3} + 12xy - 10xy= 64 - 10xy \\ {x}^{3} + {y}^{3} + 2xy = 2(32 - 5xy)$