Composition and Identity of functions

Therefore, f(g(x)) = 3x + 17.In summary, f(x) = 3x + 2 and g(x) = x + 5. When f(x) is composed with g(x), it results in 3x + 17. On the other hand, when g(x) is composed with f(x), it results in 3x + 7. This is because f(x) multiplies the input by 3 and adds 2, while g(x) simply adds 5 to the input.
  • #1
sfeld
12
0
f(x) = 3x + 2 and g(x) = x + 5

f[g(x)] but some how this equals 3x + 17? please show me.
g[f(x)] I know this would equal 3x + 7


Thanks <3
 
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  • #2
a function takes the input, performs some operation and gives an output.

f takes the input, multiplies by 3 and adds 2, now what's the input?
 
  • #3
f(x)= 3x+ 2 MEANS "what ever is inside the parentheses, multiply it by 3 and then add 2. So f(g(x))= f(x+5) means- multiply x+5 by 3 and then add 2: f(g(x))= 3(x+5)+ 2= what?

g(x)= x+ 5 MEANS "whatever is inside the parentheses, add 5 to it". g(f(x))= g(3x+2) MEANS "add 5 to 3x+ 2". What is that?
 
  • #4
f(x) = 3x + 2
g(x) = x + 5
f(g(x)) = ?

First off, let's make things easier for you and say that:
y = g(x)
which means:
f(g(x)) = f(y)

Now what is y?
y = g(x) = x + 5
And what is f(y)?
f(y) = 3y + 2
since y = g(x) = x + 5 we can replace y with x + 5
3y + 2 = 3(x + 5) + 2
Then take x + 5 out of paratheses:
3(x + 5) + 2 = 3x + 15 + 2 = 3x + 17
 

1. What is the composition of functions?

The composition of functions is the process of combining two or more functions to create a new function. It involves plugging one function into another function, where the output of the first function becomes the input of the second function.

2. How do you represent the composition of functions?

The composition of functions is represented using the notation f(g(x)), where f and g are functions and x is the input. This means that the output of g(x) becomes the input of f(x).

3. What is the difference between the composition of functions and the product of functions?

The composition of functions involves combining functions by plugging one function into another, while the product of functions involves multiplying two or more functions together. In other words, the composition of functions is a method of combining functions to create a new function, while the product of functions is a way of calculating the output of two functions multiplied together.

4. How do you find the identity of a function?

The identity of a function is a function that returns the same value as its input. In other words, the identity function is f(x) = x. To find the identity of a function, you can check if the function's output is equal to its input for all values of x.

5. What is the purpose of studying the composition of functions?

Studying the composition of functions allows us to break down complex functions into smaller, more manageable pieces. It also helps us understand how different functions interact with each other and how to manipulate them to solve problems. Additionally, the composition of functions is a fundamental concept in mathematics and is used in various fields such as physics, engineering, and computer science.

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