# What is dependent variable?

## What Does dependent variable Mean

In the field of mathematics , a symbol that is part of a proposition, an algorithm, a formula or a function and that can take different values is called a variable . According to the way in which the variable appears in the function, it can be classified as dependent or independent .

The dependent variable is one whose value depends on the numerical value adopted by the independent variable in the function. In this way, one quantity is a function of another when the value of the first quantity depends exclusively on the value shown by the second quantity. The first magnitude is the dependent variable; the second magnitude, the independent variable.

Suppose a person plans to take a car trip between London and Manchester . Both cities are 325 kilometers apart by road. The duration of the trip (which we can represent with the letter D ) will depend on the speed ( v ) of travel of the car. Duration, thus, is a variable dependent on speed, which is the independent variable.
If the journey is made at a constant speed of 120 kilometers per hour , the duration of the journey between London and Manchester will be just over 2 hours and 42 minutes . On the other hand, if the vehicle travels at 80 kilometers per hour , the duration of the trip will be extended to more than 3 hours . As can be seen, the magnitude D is a dependent variable of the magnitude v (the speed ).
The money paid to buy apples, on the other hand, depends on the quantity chosen. If the price of a kilogram of apples is 10 pesos , the total to pay will be 20 pesos if two kilograms are bought or 40 pesos if four kilograms are acquired . The amount to be paid, in this way, is a dependent variable on the quantity of apples that are bought.
In the field of geometry , where the elaboration of graphs is very common to appreciate the results of an endless number of mathematical functions, the aforementioned duality of dependent and independent variables always appears, generally under the name of y , x and z , since they are the letters associated with the Cartesian axes, although there are many used in traditional formulas, and they are taken from both our alphabet and Greek.
A very important aspect of this concept to highlight is that no variable is always dependent or independent , but rather this depends on the context in which they are used; in other words, dependency or independence is not an inherent property of any variable. To understand this particularity, we can take any of the examples set out above and modify them slightly.

In the trip from London to Manchester, since the road had already been chosen previously at the time of presenting the statement, the distance seems to be an independent variable, and the same happens with the speed. However, always on the theoretical level, what if the driver wanted to travel at a particular speed, regardless of the path he chose? What if you wanted the trip to last a fixed amount of time, and this affected speed and distance? As can be seen, the variables are like pieces of a board game, and scientists can move them as they please.
It is worth mentioning that the concept of the dependent variable and its inevitable counterpart, the independent variable, also appear outside the scope of mathematics and physics; for example, medicine and psychology can take advantage of them to measure the consequences of a treatment in a patient . In a case like this, the characteristics and properties of the treatment would be the independent variables, while the results in the subject would be the dependent ones.

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