Yes, continuous variables can be negative. For example, we generally treat temperature in as a continuous variable and temperature in the Fahrenheit or Celsius scales can have negative values. Considerably more explanation is below.
Conventionally, there are three types of variables, which can go by names other than the ones I list:
Categorical variables (which can be further sub-classified) are variables that aren't numeric in nature. So if you record the colors of a traffic light or the gender of a study subject, those are categorical in nature.
Discrete variables are those that are numeric in nature, but which have a limited resolution with which we can measure them. Common examples are counts, which can only be integers, never decimals. So if you record the number of unfilled soda cans that come out of a filling machine, you are getting discrete data.
Continuous variables can theoretically be measured with infinite precision. To be very technical, it's almost impossible to record continuous data because you'd have to be able to record an infinite number of decimal points, but in practice we can treat many different kinds of data as continuous. For example, US Dollars are conventionally only measured to two decimal points, but we can usually treat them as continuous. It turns out that for practical purposes, the key to treating data as continuous is to not have repeated values. Even count data, which are discrete by definition, can be treated as continuous in many circumstances. Look in a statistics reference for information about the normal approximation to the binomial distribution or the normal approximation to the Poisson distribution for more information.
There can be. It depends on the variables.
Negative
A continuous variable is one that can take infinite number of values in an interval. Examples are weight, height. A person's weight can be 150.2 lbs, 150.456 pounds and so on. Discrete variables, on the other hand can only assume a finite number of values. For example, number of people in a movie theatre.
The slope will be negative.The slope will be negative.The slope will be negative.The slope will be negative.
You can say that the variables are inversely proportional.
Discrete variables must be countable and not negative. So no a negative number must be a continuous variable.
The difference between continuous and discrete system lies in the variables. Whereas the continuous systems have dynamic variables, the discrete system have static variables.
It is not continuous.
Yes, if you have two limiting variables with other possibles variables between them, the variables between the limiting variables would be continuous.
Not continuous => Discrete variable. Continuous => Continuous variable.
both, variables can be anything
You age, your height, your mass, the speed at which you run, the energy you burn in doing so. They may be measured as discrete quantities but the underlying variables are all continuous.
Independent and Dependent Variables
There can be. It depends on the variables.
Continuous variables have an unlimited number of possibilities between two points. In the scientific realm, age is a continuous variable.
the value of variables is determined by the equation, discrete variables have absolute single value while the continuos have a range value
YES.