Sum of increasing and decreasing functions

In summary, the conversation discusses the possibility of expressing any real function as the sum of an increasing function and a decreasing function. The answer may depend on the continuity and differentiability of the functions, as well as the bounded variation of the function.
  • #1
chakib
1
0
i want to know if any real function can be expressed as:
f(x)=g(x)+h(x) such as g(x) is an increasing function and h(x) is a decreasing function?
thanks
 
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  • #2
Hello chakib, :welcome:

Here at PF we try to help folks to help themselves by (mostly) not providing direct answers, but providing help in the form of comments, hints, nudges, etc.

In this case: suppose you succeed, what does that mean for the derivatives of g and h ?
 
  • #3
Hi those derivatives will tell you how the functions are changing, if that helps
 
  • #4
The answer may depend on what limitations you place on f, g and h in terms of continuity and differentiability. If f is continuous I can almost trivially construct functions g and h that would satisfy your criteria but be only piecewise continuous.
 
  • #5
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What is the "sum of increasing and decreasing functions"?

The sum of increasing and decreasing functions refers to the sum of two functions that have opposite trends. One function is increasing, meaning its output values are getting larger as the input values increase. The other function is decreasing, meaning its output values are getting smaller as the input values increase. When these two functions are added together, the resulting function may have both increasing and decreasing portions.

How do you find the sum of increasing and decreasing functions?

To find the sum of increasing and decreasing functions, you simply add the two functions together. This means that for a given input value, you would calculate the output value for each function and then add those two values together to get the output value for the sum function.

What is the significance of the sum of increasing and decreasing functions?

The sum of increasing and decreasing functions is significant because it represents a balance between two opposing trends. This can be seen as a representation of equilibrium or balance in a system. It can also be used to model real-world scenarios where there are multiple factors at play, some increasing and some decreasing.

Can a function be both increasing and decreasing?

No, a function cannot be both increasing and decreasing. This is because the definition of an increasing function is that its output values are getting larger as the input values increase, while a decreasing function has output values that are getting smaller as the input values increase. However, when these two functions are added together, the resulting function may have both increasing and decreasing portions.

Can the sum of increasing and decreasing functions be a constant function?

Yes, the sum of increasing and decreasing functions can result in a constant function. This would occur when the two functions being added cancel each other out, resulting in a flat line with no change in output values for any input value. This can happen when the two functions have equal but opposite slopes.

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