What is the Definition and Purpose of Differentials in Mathematics?

In summary, dx is an infinitesimally small value of x that is used in differential calculus. It is not a real number, but rather a generic differential that represents a change in x. This value is different from zero and is essential in understanding functions and differential operators.
  • #1
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Hi everyone, this isn't a homework problem but rather just a question of definition. Is the differential (e.g. 'dx' for the 'differential of x') just when you differentiate without specifying by what you are differentiating by?
e.g. dx could stand for dx/dy, dx/dt etc.

Thanks for any help
 
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  • #2
dx does not stand for dx/dy, dx/dt, etc. dx is an infinitesimally small, positive value of x that is different from zero.
 
  • #3
That requires explanation.

dx is not a "real number" -- i.e. it is not a member of the number system you've been learning since elementary school.

But it's not unfair to consider the differentials a number system in its own right. If x denotes a "generic" real number, then dx represents a "generic" differential.

The "infinitessimalness" comes not from there being any sort of ordering to compare a differential to a real number (or even to compare two differentials) -- it comes from the fact dx dx = 0. Also, dx dy = 0 if y is dependent on x. However, if x and y are independent, then dx dy is nonzero. And this multiplication is anticommutative:
dy dx = -dx dy​




However, if you are thinking in terms of functions -- e.g. you are considering x as the function that maps a point of the line to its coordinate -- then dx acquires a related interpretation. And then, the idea of "infinitessimal number" is supplied by the differential operators.
 
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FAQ: What is the Definition and Purpose of Differentials in Mathematics?

What is the differential and why is it important in science?

The differential is a mathematical concept used to describe the rate of change of a variable with respect to another variable. It is important in science because it allows us to analyze and understand the behavior of complex systems by quantifying how one variable affects another.

How is the differential used in physics?

In physics, the differential is used to describe the relationship between position, velocity, and acceleration of objects. It is also used in equations to calculate the rate of change of physical quantities such as force, energy, and electric fields.

Can you explain the difference between a partial differential and a total differential?

A partial differential is used to describe the relationship between multiple variables in a system, while keeping all other variables constant. A total differential, on the other hand, takes into account all variables that may affect the system. In other words, a partial differential looks at how one variable affects another, while a total differential looks at how all variables together impact the system.

How is the differential used in biology?

In biology, the differential is used to study the rates of change in biological processes, such as growth, metabolism, and gene expression. It allows scientists to better understand how these processes are influenced by external factors, such as temperature, pH, and nutrient availability.

Are there any limitations to using the differential in scientific research?

While the differential is a powerful tool in scientific research, it does have some limitations. It assumes that the relationship between variables is linear and continuous, which may not always be the case in complex systems. Additionally, the differential may not accurately capture sudden or discontinuous changes in a system, such as phase transitions or abrupt shifts in behavior.

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