What does the multiply sign look like?

There are several valid forms to indicate multiplication, although some are used specificially for functions that are not simple integers.

Multiply : the letter x, not as a variable (e.g. 3 x 5 = 15)

Dot Product : (e.g. 3 . 5) -- often represented in ASCII by the asterisk (3 * 5)

Multiple of variable (e.g. 2x, 3x)

Multiplication is also indicated by parentheses and brackets, indicating successive sequences of operations, such as

(3x-2)(x-1)

[x(x-2)](x-1)