Find the value of $x^3 + y^3 - 12xy + 64$, when $x + y = -4$.

Academic Mathematics NCERT Class 9

Given:

$x + y = -4$.

To do:

We have to find the value of $x^3 + y^3 - 12xy + 64$.

Solution:

$x + y = -4$

Cubing both sides, we get,

$(x + y)^3 = (-4)^3$

$x^3 + y^3 + 3 xy(x + y) = -64$

$x^3 + y^3 + 3xy (-4) = -64$

$x^3 + y^3 - 12xy + 64 = 0$

The value of $x^3 + y^3 - 12xy + 64$ is $0$.

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Updated on: 10-Oct-2022

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