Math Problem Statement

how was the solution found

Find the domain of the function g(x) = sqrt(x) / (6x^2 + 5x - 1) using interval notation.

Solution

To find the domain of the function

g(x)=x6x2+5x1g(x) = \frac{\sqrt{x}}{6x^2 + 5x - 1}

we need to analyze two main components of the function:

  1. The square root in the numerator, x\sqrt{x}, must have a non-negative argument, so x0x \geq 0.
  2. The denominator, 6x2+5x16x^2 + 5x - 1, must not be zero because division by zero is undefined.

Step 1: Restriction from the square root

For x\sqrt{x} to be defined, we require: x0x \geq 0 This gives the preliminary condition that the domain is restricted to x0x \geq 0.

Step 2: Restriction from the denominator

Next, we need to ensure the denominator is not zero. The denominator is: 6x2+5x1=06x^2 + 5x - 1 = 0 Solving this quadratic equation using the quadratic formula: x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} Here, a=6a = 6, b=5b = 5, and c=1c = -1. Substituting into the formula: x=5±524(6)(1)2(6)x = \frac{-5 \pm \sqrt{5^2 - 4(6)(-1)}}{2(6)} x=5±25+2412x = \frac{-5 \pm \sqrt{25 + 24}}{12} x=5±4912x = \frac{-5 \pm \sqrt{49}}{12} x=5±712x = \frac{-5 \pm 7}{12} Thus, the two solutions are: x=5+712=212=16x = \frac{-5 + 7}{12} = \frac{2}{12} = \frac{1}{6} x=5712=1212=1x = \frac{-5 - 7}{12} = \frac{-12}{12} = -1

The denominator is zero when x=16x = \frac{1}{6} and x=1x = -1. Since x=1x = -1 is excluded from the domain because of the square root, we only need to exclude x=16x = \frac{1}{6}.

Step 3: Combine the conditions

The function is defined for x0x \geq 0, except at x=16x = \frac{1}{6}. Therefore, the domain is:

[0,16)(16,)[0, \frac{1}{6}) \cup (\frac{1}{6}, \infty)

This is the interval notation solution provided.


Would you like further details on any part of the process? Here are some related questions:

  1. How do you solve quadratic equations in general?
  2. What is the significance of excluding 16\frac{1}{6} from the domain?
  3. Why must x0x \geq 0 for the square root function to be defined?
  4. How does the quadratic formula work in this context?
  5. What other techniques can be used to find the domain of a function?

Tip: Always check both the numerator and denominator when finding the domain of a rational function.

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Math Problem Analysis

Mathematical Concepts

Algebra
Rational Functions
Quadratic Equations

Formulas

Quadratic formula: x = [-b ± sqrt(b^2 - 4ac)] / 2a
Domain restrictions: Square root function must have non-negative arguments (x >= 0), Denominator cannot be zero

Theorems

Quadratic formula
Properties of square root functions
Domain of rational functions

Suitable Grade Level

Grades 9-12