Math  /  Algebra

QuestionConsider the following functions. f(x)=1xf(x) = \frac{1}{x} and g(x)=x1g(x) = x - 1
Step 2 of 2: Find the formula for (gf)(x)(g \circ f)(x) and simplify your answer. Then find the domain for (gf)(x)(g \circ f)(x). Round your answer to two decimal places, if necessary.
Answer 2 Points
(gf)(x)=(g \circ f)(x) =
Domain ==

Studdy Solution

STEP 1

What is this asking? We're taking two functions, f(x)f(x) and g(x)g(x), and we need to find the function (gf)(x)(g \circ f)(x), which is the same as g(f(x))g(f(x)), and then figure out what values of xx are allowed. Watch out! Remember, (gf)(x)(g \circ f)(x) means we're putting f(x)f(x) *inside* g(x)g(x)!
Also, be super careful about the domain; we need to make sure the resulting function makes sense!

STEP 2

1. Compose the functions
2. Find the domain

STEP 3

Alright, let's **start** by remembering what (gf)(x)(g \circ f)(x) *actually means*.
It means we're taking f(x)f(x) and plugging it into g(x)g(x) wherever we see an xx.
So, since g(x)=x1g(x) = x - 1, we're going to replace that xx with the whole function f(x)f(x), which is 1x\frac{1}{x}.

STEP 4

So, (gf)(x)(g \circ f)(x) becomes g(f(x))=1x1g(f(x)) = \frac{1}{x} - 1.
Boom! That's our **composed function**!

STEP 5

Now, for the **domain**.
Remember, the domain is all the possible xx values we can plug in.
Let's look at our original functions.
For f(x)=1xf(x) = \frac{1}{x}, we can't have x=0x = 0 because we can't divide by **zero**.
For g(x)=x1g(x) = x - 1, we can plug in *anything*!

STEP 6

But now, we have (gf)(x)=1x1(g \circ f)(x) = \frac{1}{x} - 1.
We still can't have x=0x = 0 because of that 1x\frac{1}{x}.
So, our **domain** is all real numbers *except* 00!
We can write that as (,0)(0,)(-\infty, 0) \cup (0, \infty).
That means everything from negative infinity up to 0, *and* everything from 0 to positive infinity!

STEP 7

(gf)(x)=1x1(g \circ f)(x) = \frac{1}{x} - 1
Domain =(,0)(0,)= (-\infty, 0) \cup (0, \infty)

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