1
algebra

How many solutions does this system have? {2x+3y=64x+6y=12\begin{cases} 2x + 3y = 6 \\ 4x + 6y = 12 \end{cases}

A

No solution

B

Exactly one solution

C

Infinitely many solutions

D

Exactly two solutions

Correct Answer: C

Choice C is the correct answer. Notice that the second equation is exactly double the first equation.

Step 1: Multiply the first equation by 2: 2(2x+3y)=2(6)2(2x + 3y) = 2(6)4x+6y=124x + 6y = 12

This is identical to the second equation! The two equations represent the same line.

Step 2: Since both equations describe the same line, every point on that line is a solution. đź’ˇ Strategic Tip: When one equation is a multiple of the other, the system has infinitely many solutions (coincident lines).

Choice A is incorrect because the lines are identical, not parallel. Parallel lines with different y-intercepts have no solution.

Choice B is incorrect because systems have exactly one solution only when the lines intersect at a single point (different slopes).

Choice D is incorrect because two linear equations can never have exactly two solutions—they either don't intersect (0 solutions), touch at one point (1 solution), or are the same line (infinite solutions).