Question

find the value of x³+y³-12xy+64 when x+y=-4​

Answer 1

hope it may be helpful

the values is zero

Answer 2

x³ + y³ - 12xy + 64

= x³ + y³ + 4³ - 3(4xy)                      

...(As 64 = 4³)

= (x + y + 4)(x² + y² + 4²  - xy - 4y - 4x)    

...[As x³ + y³ + z³ - 3xyz = (x + y + z)(x² + y² + z² - xy - yz - xz]

x + y = - 4

(Given)

= (- 4 + 4) * (x² + y² + 4²  - xy - 4y - 4x)

= 0 * (x² + y² + 4²  - xy - 4y - 4x)

= 0