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Set 6: Systems of Equations (Intermediate)

Explanation

Answer: C

Which describes the lines in this system? {2x3y=64x6y=12\begin{cases} 2x - 3y = 6 \\ 4x - 6y = 12 \end{cases}

A.

The lines intersect at one point

B.

The lines are perpendicular

C.

The lines are identical

✓ Correct
D.

The lines are parallel but not identical

Detailed Explanation

Choice C is correct. Choice C is the correct answer. Step 1: Multiply the first equation by 2: $$2(2 x - 3 y) = 2(6)4x - 6 y = 12$$$ This is exactly the second equation! Step 2: Since both equations represent the same line, they are identical (coincident). This means infinitely many solutions—every point on the line satisfies both equations. Strategic Tip: Identical lines are a special case of "infinitely many solutions." Choice A is incorrect because intersecting at one point requires different slopes. Choice B is incorrect because perpendicular lines have slopes whose product is -1.Here,bothhaveslope. Here, both have slope \frac{2}{3}$. Choice D is incorrect because the lines are not just parallel—they're the same line.

Key Steps:

The correct answer is The lines are identical

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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