roots of polynomial

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To display inline code, like expr = x*y*z, use backticks.

For instance, compare the input and output without backticks:

Having defined expr = x*y*z, how do I recover the individual factors?

Having defined expr = xyz, how do I recover the individual factors?

to the ones with backticks:

Having defined `expr = x*y*z`, how do I recover the individual factors?

Having defined expr = x*y*z, how do I recover the individual factors?

Notice how in one case the * are preserved, while in the other case they just make the y italics.

To display blocks of code or error messages, skip a line above and below, and do one of the following (all give the same result):

• indent all code lines with 4 spaces
• select all code lines and click the "code" button (the icon with '101 010')
• select all code lines and hit ctrl-K

For instance, typing

If we define `f` by

    def f(x, y, z):
        return x * y * z

then `f(2, 3, 5)` returns `30` but `f(2*3*5)` gives:

    TypeError: f() takes exactly 3 arguments (1 given)

produces:

If we define f by

def f(x, y, z):
    return x * y * z

then f(2, 3, 5) returns 30 but f(2*3*5) gives:

TypeError: f() takes exactly 3 arguments (1 given)

Could you edit your question to take these points into account?

Please also keep that in mind for future questions.

It makes the code display correctly, and makes it possible to copy and paste.

In that way it helps other users who try to answer your questions.

Please include complete code that allows to reproduce the input and output in the question.

For example, you probably defined a in some way, which you did not provide.