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Question:

If x+y+z=0, show that x³+y³+z³=3xyz

Solution:

We know that x³+y³+z³−3xyz=(x+y+z)(x²+y²+z²−xy−yz−zx)
Given x+y+z=0
x³+y³+z³−3xyz=(0)(x²+y²+z²−xy−yz−zx)
⇒x³+y³+z³−3xyz=0
⇒x³+y³+z³=3xyz
Hence proved.