Generally speaking, the positive terminal is usually on the left when the speaker is facing up. On our neodymium models, this is opposite. The positive terminal is marked in red on the right when the speaker is facing up. If the cone moves in, the positive battery lead is connected to the speaker's negative terminal.
Is the marked speaker wire positive or negative?
The solid/dashed lines on wires like the ones pictured in your question are used to indicate polarity e.g. for the "wall wart" power supplies. Usually* the wire with the white stripe or the dashed lines carries the "positive" (+) end, while the other, unmarked wire carries the "negative" (-) end.
Is the red speaker wire positive or negative?
These terminals are also almost always color-coded for easy identification: The positive terminal (+) is typically red, while the negative terminal (-) is typically black. Note that some speakers are bi-wire capable, which means the red and black terminals come in pairs for a total of four connections.