toán nâng cao 8

L

luffy_1998

x+y+z=0→x=−(y+z)x+y+z=0 \rightarrow x = - (y + z)
→x3+y3+z3=−(y+z)3+y3+z3=−3y2z−3yz2=−3yz(y+z)=3xyz\rightarrow x^3+y^3+z^3 = - (y + z)^3 + y^3 + z^3 = - 3y^2z - 3yz^2 = -3yz(y + z) = 3xyz
 
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