Math Problem Statement

Which of the following gives a valid reason for using the given solution method to solve the system of equations shown?

Equation I: 4x − 5y = 4 Equation II: 2x + 3y = 2

A. Elimination; a coefficient in Equation I is an integer multiple of a coefficient in Equation II. B. Elimination; a coefficient in Equation II is an integer multiple of a coefficient in Equation I. C. Substitution; Equation I can be solved for x in one step by dividing both sides by 4. D. Substitution; Equation II can be solved for x in one step by subtracting 3y from both sides.

Solution

The correct answer is:

D. Substitution; Equation II can be solved for x in one step by subtracting 3y from both sides.

Explanation:

To decide the appropriate method, let’s review each option in light of the system of equations:

  1. Option A: "Elimination; a coefficient in Equation I is an integer multiple of a coefficient in Equation II."

    • This is incorrect because none of the coefficients in Equation I are multiples of the corresponding coefficients in Equation II (for example, 4 is not a multiple of 2, and -5 is not a multiple of 3).
  2. Option B: "Elimination; a coefficient in Equation II is an integer multiple of a coefficient in Equation I."

    • This is also incorrect for the same reason as above. None of the coefficients in Equation II are integer multiples of those in Equation I.
  3. Option C: "Substitution; Equation I can be solved for x in one step by dividing both sides by 4."

    • This is incorrect because solving for xx in Equation I would require additional steps beyond dividing by 4. We would first need to isolate xx by adding or subtracting terms.
  4. Option D: "Substitution; Equation II can be solved for x in one step by subtracting 3y from both sides."

    • This is correct. In Equation II, we can isolate xx by subtracting 3y3y from both sides to get: 2x=23y2x = 2 - 3y
    • This allows for substitution directly by isolating xx after an additional division by 2.

Final Answer: D

Would you like a breakdown of solving this system or further clarification?


Related Questions:

  1. How does the elimination method work for systems of equations?
  2. What are common indicators that substitution is the best method for solving a system?
  3. What steps would be involved if we chose the elimination method for this system?
  4. Can we solve this system using matrix methods?
  5. How does graphing the equations provide a solution to this system?

Tip: When deciding between elimination and substitution, look at the complexity of isolating one variable—if one equation can isolate a variable easily, substitution is often advantageous.

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Math Problem Analysis

Mathematical Concepts

Systems of Linear Equations
Substitution Method
Elimination Method

Formulas

Solving for a variable in linear equations
Elimination and Substitution methods

Theorems

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Suitable Grade Level

Grades 8-10