5

Set 13: Systems of Equations (Advanced)

Explanation

Answer: C

Which statement is true? {3x+y=126x+2y=20\begin{cases} 3x + y = 12 \\ 6x + 2y = 20 \end{cases}

A.

The system has infinitely many solutions

B.

The system has exactly one solution

C.

The system has no solution

✓ Correct
D.

The lines are perpendicular

Detailed Explanation

Choice C is correct. Choice C is the correct answer. Step 1: Multiply the first equation by 2: 2(3 x + y) = 2(12)$6x + 2 y = 24$$$ Step 2: Compare with the second equation: - Our result: 6x + 2 y = 24Given:- Given:6x + 2 y = 20ThisgivesusThis gives us24= 20$$, which is impossible! Conclusion: The lines are parallel but don't overlap → no solution Strategic Tip: When simplification leads to a false statement (like 24 = 20), the system has no solution. Choice A is incorrect because infinite solutions require both sides to match completely. Choice B is incorrect because one solution requires different slopes. Choice D is incorrect because both lines have slope 3-3, not perpendicular slopes.

Key Steps:

The correct answer is The system has no solution

Why others are wrong:
A: Choice A is incorrect and may result from a calculation error.
B: Choice B is incorrect and may result from a calculation error.
D: Choice D is incorrect and may result from a calculation error.

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