Math Problem Statement

find the domain and the range of the function below: g(x) = x+3/x^2+1

Solution

We are given the function:

g(x)=x+3x2+1g(x) = \frac{x + 3}{x^2 + 1}

1. Finding the Domain

The domain of a function consists of all possible xx-values for which the function is defined. For rational functions like g(x)g(x), the main issue is division by zero. So, we check if the denominator can ever be zero.

The denominator is x2+1x^2 + 1. This expression is never zero because:

x2+11for all real values of xx^2 + 1 \geq 1 \quad \text{for all real values of } x

Thus, the denominator is always positive and non-zero. Therefore, there are no restrictions on xx, meaning that the domain is:

Domain of g(x):(,)\text{Domain of } g(x): \quad (-\infty, \infty)

2. Finding the Range

To find the range, we need to determine the possible values of g(x)g(x). The function:

g(x)=x+3x2+1g(x) = \frac{x + 3}{x^2 + 1}

We can analyze the behavior of the function as xx \to \infty and xx \to -\infty:

  • As xx \to \infty, the x2x^2 term dominates in the denominator, so:

g(x)xx2=1xg(x)0g(x) \approx \frac{x}{x^2} = \frac{1}{x} \quad \Rightarrow \quad g(x) \to 0

  • As xx \to -\infty, the same logic applies, so g(x)0g(x) \to 0 as xx \to -\infty.

Thus, the function approaches 00, but never reaches it.

Next, we check specific values to see if other values are possible. For example:

  • At x=0x = 0:

g(0)=0+302+1=3g(0) = \frac{0 + 3}{0^2 + 1} = 3

  • For large positive and negative values of xx, g(x)g(x) can get arbitrarily close to 00, but never reach it.

Therefore, the function covers values from 00 (but not including 00) up to a maximum of 3 (or even higher depending on exact values). Based on this, the range is:

Range of g(x):(,)\text{Range of } g(x): \quad (-\infty, \infty)

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Math Problem Analysis

Mathematical Concepts

Algebra
Functions
Domain and Range
Rational Functions
Limits

Formulas

g(x) = (x + 3)/(x^2 + 1)

Theorems

Limits as x approaches infinity and negative infinity
Properties of rational functions

Suitable Grade Level

Grades 10-12