Math Problem Statement

The range of the function y = √(x^2 + 4x + 2) - 1 is…

Solution

The image shows a problem asking for the range of the function y=x2+4x+21y = \sqrt{x^2 + 4x + 2} - 1. Here's how to find the range of this function:

Step-by-Step Solution:

  1. Analyze the Function Inside the Square Root: The function inside the square root is x2+4x+2x^2 + 4x + 2, which is a quadratic expression. The expression inside the square root must be non-negative, so we start by analyzing this quadratic.

  2. Find the Vertex of the Quadratic: The expression x2+4x+2x^2 + 4x + 2 can be rewritten by completing the square: x2+4x+2=(x2+4x+4)4+2=(x+2)22x^2 + 4x + 2 = (x^2 + 4x + 4) - 4 + 2 = (x + 2)^2 - 2 The vertex of this parabola occurs at x=2x = -2, and the minimum value of the quadratic function is (x+2)22(x + 2)^2 - 2. At x=2x = -2, the minimum value is: (x+2)22=(0)22=2(x + 2)^2 - 2 = (0)^2 - 2 = -2

  3. Determine the Minimum Value Under the Square Root: Since the square root function requires non-negative inputs, the expression x2+4x+2x^2 + 4x + 2 must be greater than or equal to zero. But, the lowest value of x2+4x+2x^2 + 4x + 2 is -2, so: x2+4x+2 is defined for x2+4x+20\sqrt{x^2 + 4x + 2} \text{ is defined for } x^2 + 4x + 2 \geq 0

    To ensure this, add 2 to both sides: x2+4x+2+22x2+4x+22x^2 + 4x + 2 + 2 \geq 2 \quad \Rightarrow \quad \sqrt{x^2 + 4x + 2} \geq \sqrt{2}

  4. Range Calculation: Since x2+4x+22\sqrt{x^2 + 4x + 2} \geq \sqrt{2}, then the function y=x2+4x+21y = \sqrt{x^2 + 4x + 2} - 1 will always be at least: y21y \geq \sqrt{2} - 1

    As x2+4x+2x^2 + 4x + 2 grows, so does the square root, meaning there is no upper bound on yy.

Conclusion:

The range of the function y=x2+4x+21y = \sqrt{x^2 + 4x + 2} - 1 is ( [\

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Function Range
Square Roots

Formulas

Quadratic Formula: ax^2 + bx + c
Completing the Square
Square Root Function

Theorems

Vertex Formula for Quadratic Equations
Properties of Square Roots

Suitable Grade Level

Grades 10-12