In terms of eNotes rules, please note that you cannot post multiple questions. These are completely separate questions but can be answered using the same principle as explained above.
`a^3+b^3+c^3-3abc` = `(a+b+c)(a^2+b^2+c^2-ab-bc-ca)`
Expand the RHS (right-hand side):
RHS= `a^3 +ab^2+ac^2-a^2b-abc-a^2c >`
`` `+a^2b+b^3+bc^2-ab^2-b^2c-abc >`
Rearrange and reduce. Note how the positive terms cancel out the negative terms leaving:
`therefore = a^3+b^3+c^3-3abc`
Ans: LHS = RHS. By expanding the right-hand side, you can show that it is equal to the left hand side.
Thank you very much!I understand and i'm sorry for this.I didn't know the rules.