Math Problem Statement

Calcola il dominio e intersezioni

Calcola il dominio e intersezioni

Solution

The expression in the image is:

y=x+1xy = -\sqrt{\frac{x + 1}{x}}

Let's first calculate the domain of this function:

Step 1: Set conditions for the square root

The expression inside the square root must be non-negative, i.e.:

x+1x0\frac{x + 1}{x} \geq 0

This inequality can be solved by analyzing the critical points where the numerator and denominator are zero:

  • The numerator x+1=0x + 1 = 0 implies x=1x = -1.
  • The denominator x=0x = 0 is undefined, so we must exclude x=0x = 0 from the domain.

Now, analyze the sign of the fraction in the intervals determined by these points:

  • For x<1x < -1, both x+1<0x + 1 < 0 and x<0x < 0, so the fraction is positive.
  • For 1<x<0-1 < x < 0, x+1>0x + 1 > 0 but x<0x < 0, so the fraction is negative.
  • For x>0x > 0, both x+1>0x + 1 > 0 and x>0x > 0, so the fraction is positive.

Thus, the inequality holds for x(,1](0,)x \in (-\infty, -1] \cup (0, \infty).

Step 2: Consider the square root

Since we are dealing with a square root, the expression is defined where x+1x0\frac{x+1}{x} \geq 0, excluding x=0x = 0, as already determined. Therefore, the domain of the function is:

(,1](0,)\boxed{(-\infty, -1] \cup (0, \infty)}

Step 3: Intersections with axes

  1. Intersection with the y-axis: To find the intersection with the y-axis, we evaluate the function at x=0x = 0, but since x=0x = 0 is excluded from the domain, there is no intersection with the y-axis.

  2. Intersection with the x-axis: The function will intersect the x-axis when y=0y = 0. Set the function equal to zero:

    x+1x=0-\sqrt{\frac{x+1}{x}} = 0

    This implies that the expression inside the square root must be zero:

    x+1x=0\frac{x+1}{x} = 0

    Solving this gives x+1=0x + 1 = 0, or x=1x = -1. Therefore, the intersection with the x-axis is at the point:

    (1,0)(-1, 0)

Summary:

  • Domain: (,1](0,)(-\infty, -1] \cup (0, \infty)
  • Intersection with the x-axis: (1,0)(-1, 0)
  • Intersection with the y-axis: None (since x=0x = 0 is excluded from the domain)

Would you like further details or have any questions?

Here are some related questions to explore:

  1. How do we handle square root functions when determining the domain?
  2. Why is x=0x = 0 excluded from the domain of this function?
  3. What happens when x=1x = -1 and why is it a critical point?
  4. How can the function behavior be analyzed as xx approaches infinity?
  5. What kind of transformation does the negative sign outside the square root introduce?

Tip: When dealing with square roots in functions, always remember that the radicand must be non-negative to define the function properly!

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Math Problem Analysis

Mathematical Concepts

Function Analysis
Domain
Intersections
Square Root Function
Inequalities

Formulas

y = -√((x + 1)/x)
Domain of √(expression) is when expression ≥ 0
Intersection with x-axis: y = 0

Theorems

Properties of Rational Functions
Square Root Function Domain
Sign Analysis of Rational Expressions

Suitable Grade Level

Grades 10-12