Math Problem Statement

domain of root(-x+50)/11 - 4/(-22-x)

Solution

To find the domain of the function:

f(x)=x+5011422xf(x) = \sqrt{\frac{-x + 50}{11} - \frac{4}{-22 - x}}

We need to determine when the expression inside the square root is non-negative, as square roots of negative numbers are not defined in the set of real numbers. Additionally, the denominators cannot be zero because division by zero is undefined.

Step-by-Step Process:

  1. First term: x+5011\frac{-x + 50}{11} This expression is defined for all xx, as the denominator is a constant (11), so there is no risk of division by zero.

  2. Second term: 422x\frac{4}{-22 - x} This expression is undefined when the denominator equals zero, i.e., when: 22x=0x=22-22 - x = 0 \quad \Rightarrow \quad x = -22 Therefore, x=22x = -22 must be excluded from the domain.

  3. Non-negativity of the entire expression: We need the entire expression under the square root to be non-negative: x+5011422x0\frac{-x + 50}{11} - \frac{4}{-22 - x} \geq 0 We solve this inequality to find the valid values of xx.

Step 1: Combine the two terms.

Get a common denominator: x+5011422x=(x+50)(22x)4411(22x)\frac{-x + 50}{11} - \frac{4}{-22 - x} = \frac{(-x + 50)(-22 - x) - 44}{11(-22 - x)}

Simplify the numerator: (x+50)(22x)=x2+22x1100(-x + 50)(-22 - x) = x^2 + 22x - 1100 So the numerator becomes: x2+22x110044=x2+22x1144x^2 + 22x - 1100 - 44 = x^2 + 22x - 1144

Now, the inequality becomes: x2+22x114411(22x)0\frac{x^2 + 22x - 1144}{11(-22 - x)} \geq 0

Step 2: Solve the inequality.

To find the solution to this inequality, analyze the sign changes of the expression:

  1. The numerator is x2+22x1144x^2 + 22x - 1144, a quadratic function that will have roots at specific points.
  2. The denominator changes sign at x=22x = -22, which is already excluded from the domain.

By solving x2+22x1144=0x^2 + 22x - 1144 = 0, we can find critical points and intervals to test for the inequality.

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Math Problem Analysis

Mathematical Concepts

Algebra
Rational Functions
Inequalities
Square Roots
Quadratic Equations

Formulas

Rational function: (a/x) - (b/y)
Quadratic equation: ax^2 + bx + c = 0
Inequality solving

Theorems

Quadratic formula: x = (-b ± sqrt(b^2 - 4ac)) / 2a
Non-negativity condition for square roots
Exclusion of values where the denominator is zero

Suitable Grade Level

Grades 10-12