# All Questions

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### Solve that equation [on hold]

Solve equations - $\sqrt{\frac{x+7}{x+1}}+8=2x^2+\sqrt{2x-1}$ $\sqrt{\frac{6}{3-x}}+\sqrt{\frac{8}{2-x}}=6$ $\sqrt[3]{2x+1}-\sqrt[3]{3x^2+x-1}=\sqrt{x}-1$
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### What is the error in this fake-proof of the complex number i? [duplicate]

The error is from the 3rd step to the 4th step. But why is this an error? Can't $i$ be interchangeable with $\sqrt{-1}$? $-1 = i\cdot i = \sqrt{-1}\cdot \sqrt{-1} = \sqrt{(-1)(-1)} = \sqrt{1} = 1$