Can we show this quartic equation has exactly two real roots?

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Sketch in the same diagram the graphs of \(y = x^2\) and \(x^2 + y^2 - 4x + 2y - 4 = 0\). Hence or otherwise show that the equation \(x^4 + 3x^2 - 4x - 4 = 0\) has two and only two real roots.

Find the positive root of the equation correct to one decimal place.