I need to revolve this parabola $360$ degrees about the $y$ axis (to find volume of revolution).
$y = -0.399x^2 + 0.0232x + 5.68$
But I cannot express it in the form $x^2 = f(y)$, which is required for the integration calculation.
Can someone help me find the correct expression? I have no idea about how to leave $x^2$ alone and write it in terms of $y$...