Question

find the value of x³ +y³ -2xy +64 when x+y = -4​

Answer 1

Answer:

Step-by-step explanation:

Given

x+y= -4

Now$(x+y)^3 =(-4)^3\\\\x^3+y^3+3xy(x+y)=-64\\\\x^3+y^3+3xy(-4)+64=0\\\\x^3+y^3-12xy+64=0\\\\Therefore\\\\x^3+y^3-12xy+64=0\\\\\\\\\\Formulae\\\\(a+b)^3=a^3+b^3+3ab(a+b)$

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