Yes, you can have more than one variable
yes it can I've done a few experiments that have had more than one independant variable.
A variable can not hold more than one value at any given moment in time. It would have only one. If you wanted more than one value, you would have to make the variable an array.
You can have more than one variable, but it would take longer to solve.
A variable measured at the interval or ratio level can have more than one arithmetic mean.
No.
Actually, you have two - dependent and independent. But, you only have one variable because otherwise the answer wouldn't be accurate if you had more than one variable.
It really depends on what the experiment is.
A bivariate equation.
more than one variable
add one to the problem
Ordinary Diff -> One variable Partial Diff -> More than one variable
Yes you can, but the more variables you have the more complex the problem becomes.