German math Olympiad. Intriguing tricks used to solve an Olympiad math problem

This is really an interesting video showing how simple tricks could be used to solve Olympiad problems on radicals.
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[@Birol731]

Interesting question, thank you very much for sharing 🙏👌

[@begechorimaths2975]

@@Birol731 👊🙏

[@sy8146]

Thank you for explaining. I have a question. If we use " f(x)≧0 for √f(x) ", x=2 should be rejected because all values "inside of the √ " are negative. If x=2 is one of the solutions, I guess the problem admits complex numbers. (: The reason of rejection is not "Not Real.") ・・・ If x=2, (the left side) = 3√2 i + 2√2 i and (the right side) = 5√2 i . Thus, it can satisfy the equation (, but it is not real numbers.) And, even if the complexed numbers are admitted, if x=-5/3, (the left side) = (4√17)/3 i + (√17)/3 i and (the right side) = (√17) i . Thus, it does NOT satisfy the equation. Therefore, I guess the reason why x=-5/3 is rejected in this video is a little different. > (My question is "which condition is the original problem requiring?" )