What’s the answer of 5x^(2/3) -25=0 ? Is it +5sqrt(5) or +-5sqrt(5)

Question

I have this question in my head when the teacher said it’s +-5sqrt(5) while WolframAlpha said that it’s +5sqrt(5). The main problem is what’s the value of (-1)^(2/3)? I plugged this in Google and the answer is -0.5+0.866i while the texas instruments calculator showed me 1.

Answer 1

5x^2/3 - 25 = 0

5x^2/3 = 25

x^2/3 = 5

x² = 125

x = ±5√5

 

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