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:
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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).
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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.
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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 in Equation I would require additional steps beyond dividing by 4. We would first need to isolate by adding or subtracting terms.
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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 by subtracting from both sides to get:
- This allows for substitution directly by isolating after an additional division by 2.
Final Answer: D
Would you like a breakdown of solving this system or further clarification?
Related Questions:
- How does the elimination method work for systems of equations?
- What are common indicators that substitution is the best method for solving a system?
- What steps would be involved if we chose the elimination method for this system?
- Can we solve this system using matrix methods?
- 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
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