Question

Compare f(x)= square root x+1 and g(x) = ^3 square root x +1
Both are increasing in their domain
Both have the same range (- infinity, infinity)
Both go through points (-1,0) and (0,1)
Both have the same domain, x> 0

Answers

GPT-4o mini
Let’s analyze the two functions \( f(x) = \sqrt{x} + 1 \) and \( g(x) = \sqrt[3]{x} + 1 \) based on the claims you've made.

1. **Domain**:
- \( f(x) = \sqrt{x} + 1 \) has a domain of \( x \geq 0 \) because the square root function is defined only for non-negative real numbers.
- \( g(x) = \sqrt[3]{x} + 1 \) has a domain of all real numbers \( (-\infty, \infty) \) because the cube root function is defined for all real numbers.
- Therefore, the statement that both functions have the same domain \( x > 0 \) is incorrect, as \( g(x) \) is defined for all \( x \).

2. **Range**:
- \( f(x) = \sqrt{x} + 1 \) has a range of \( [1, \infty) \) because as \( x \) increases from 0 to infinity, \( f(x) \) starts at 1 (when \( x = 0 \)) and increases without bound.
- \( g(x) = \sqrt[3]{x} + 1 \) has a range of \( (-\infty, \infty) \) because as \( x \) approaches negative infinity, \( g(x) \) also approaches negative infinity; and as \( x \) approaches positive infinity, \( g(x) \) approaches positive infinity.
- Thus, both functions do not have the same range, contradicting the statement.

3. **Increasing Behavior**:
- Both \( f(x) \) and \( g(x) \) are increasing functions in their respective domains.
- \( f(x) \) is increasing for \( x \geq 0 \).
- \( g(x) \) is increasing for all \( x \).
- This claim is correct.

4. **Points (-1, 0) and (0, 1)**:
- Neither function passes through the point (-1, 0):
- \( f(-1) = \sqrt{-1} + 1 \) is undefined.
- \( g(-1) = \sqrt[3]{-1} + 1 = -1 + 1 = 0 \).
- The point **(0, 1)** is valid for both functions:
- \( f(0) = \sqrt{0} + 1 = 1 \).
- \( g(0) = \sqrt[3]{0} + 1 = 1 \).
- Only the point \( (0, 1) \) is correct for both functions, while the point (-1, 0) is not valid for \( f(x) \).

### Summary:
- The functions **do not** have the same domain.
- They have **different ranges**.
- Both functions are indeed **increasing** in their respective domains.
- They share the point **(0, 1)** and do not intersect at (-1, 0).

### Corrected Statements:
- The domains are \( x \geq 0 \) for \( f(x) \) and \( x \in (-\infty, \infty) \) for \( g(x) \).
- The ranges are \( [1, \infty) \) for \( f(x) \) and \( (-\infty, \infty) \) for \( g(x) \).
- Both are increasing in their respective domains.
- Both pass through the point (0, 1), but only one function \( g(x) \) passes through (−1, 0).