7
algebra

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

D

The lines are parallel but not identical

Correct Answer: C

Choice C is the correct answer. Let's check the relationship.

Step 1: Multiply the first equation by 2: 2(2x3y)=2(6)2(2x - 3y) = 2(6)4x6y=124x - 6y = 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 1-1. Here, both have slope 23\frac{2}{3}.

Choice D is incorrect because the lines are not just parallel—they're the same line.