Why does Mathematica just return Hold of my Input? [closed]

Example:

Solve[x^2 + a x + 1 == 0, x]

Output: Hold[Solve[x^2 + a x + 1 == 0, x]]

What is the problem? Any child can solve this in its head

closed as off-topic by march, LCarvalho, m_goldberg, user21, user42582Jun 15 at 12:44

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• "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – march, LCarvalho, m_goldberg, user21, user42582
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• For me it works. Have you tried stopping the kernel prior to this? – Gladaed Jun 11 at 11:56
• I don't know how but restarting Mathematica solved the problem... Still curious why this happened – OD IUM Jun 11 at 11:58
• You must have assigned some value to x that causes the code to loop. Just like what happens when you assign x = x + 1. – Sjoerd Smit Jun 11 at 13:04

Solve[x^2 + a x + 1 == 0, x]

gives the correct answer. Unless x or a are defined. It is pretty much guaranteed to return the correct answer if you Clear the symbols prior to execution or use a Block.

x = 1
a = 1
Solve[x^2 + a x + 1 == 0, x]

does not work, even if only x is defined. This is actually fairly confusing and might be because the expression does not get properly Hold 'ed. Be Aware!

x = 1
a = 1
Clear[a,x]
Solve[x^2 + a x + 1 == 0, x]

does

x = 1
a = 1
Block[{a, x},
Solve[x^2 + a x + 1 == 0, x]]
{x, a}

does aswell while preserving any potential values of both x and a