Can affine functions form a group under function composition?

In summary, the set A = (f:R-->R such that f(x)=mx+b, m not= 0) of affine functions from R to R forms a group under composition of function. To prove this, one must apply the composition of functions property and show that the resulting function is also an affine function. This can be achieved by taking two arbitrary elements of the group, composing them, and showing that the resulting function also satisfies all of the group axioms.
  • #1
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Homework Statement


Show that the set A = (f:R-->R such that f(x)=mx+b, m not= 0} of affine functions from R to R forms a group under composition of function.

The Attempt at a Solution


Obviously I need to apply the composition of functions property (f: S->T, g:T->U, g of is function from S to U defined by g(f(x)) for all x element of S), but I'm not sure how to take the first step.
 
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  • #2
Take two arbitrary elements of the group, compose them and show what you get must also be in the group.

That's one of the first steps. You need to show it satisfies all of the group axoims for the full proof.
 
Last edited:
  • #3
Thanks, solved!
 

1. What is an affine function?

An affine function is a mathematical function that combines both linear and constant terms. It can be written in the form f(x) = mx + b, where m is the slope or rate of change, and b is the y-intercept or initial value.

2. How do affine functions form a group?

A group is a mathematical structure that follows certain rules and properties, including closure, associativity, identity, and inverse. Affine functions form a group under composition, meaning that when two affine functions are composed, the result is also an affine function and it follows the group properties.

3. What is the significance of affine functions forming a group?

The fact that affine functions form a group is significant because it allows for the manipulation and combination of these functions to solve mathematical problems. This is particularly useful in fields such as geometry, physics, and computer science.

4. How are affine functions used in real life?

Affine functions have many real-life applications, including in economics, where they can model relationships between variables such as supply and demand. They are also used in computer graphics to create 3D images and animations, and in physics to describe the motion of objects.

5. Can you give an example of an affine function?

One example of an affine function is f(x) = 2x + 5. This function has a slope of 2 and a y-intercept of 5. When x = 0, the function has a value of 5, and for every increase of 1 in x, the value of the function increases by 2. This can be represented graphically as a straight line with a positive slope passing through the point (0, 5).

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