10

Set 16: Systems of Equations (Intermediate)

Explanation

Answer: A

Which system has no solution?

I. {y=2x+3y=2x1\begin{cases} y = 2x + 3 \\ y = 2x - 1 \end{cases}

II. {y=2x+3y=2x+3\begin{cases} y = 2x + 3 \\ y = -2x + 3 \end{cases}

III. {y=2x+32y=4x+6\begin{cases} y = 2x + 3 \\ 2y = 4x + 6 \end{cases}

A.

I only

✓ Correct
B.

II only

C.

III only

D.

I and II only

Detailed Explanation

Choice A is correct. Choice A is the correct answer. System I: y=2x+3y = 2 x + 3 and y=2x1y = 2 x - 1 - Same slope (2), different y-intercepts (3 and -1) - Parallel lines → No solution ✓ System II: y=2x+3y = 2 x + 3 and y=2x+3y = -2 x + 3 - Different slopes (2 and -2) - Intersecting lines → One solution System III: y=2x+3y = 2 x + 3 and 2y=4x+62y = 4 x + 6 - Divide second by 2: y=2x+3y = 2 x + 3 - Same line → Infinitely many solutions Conclusion: Only System I has no solution. Strategic Tip: - Same slope, different intercepts → No solution - Different slopes → One solution - Same equation → Infinitely many solutions Choice B is incorrect because System II has one solution (lines intersect). Choice C is incorrect because System III has infinitely many solutions (same line). Choice D is incorrect because System II has one solution.

Key Steps:

The correct answer is I only

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