9

Set 10: Linear Functions (Intermediate)

Explanation

Answer: A

A line passes through the origin and (3,−1)(3, -1). What is its equation?

A.

y=−13xy = -\frac{1}{3}x

✓ Correct
B.

y=−3xy = -3x

C.

y=13xy = \frac{1}{3}x

D.

y=3xy = 3x

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Find slope. 1. Points: (0,0)(0, 0) and (3,−1)(3, -1). 2. Slope: −1−03−0=−13\frac{-1 - 0}{3 - 0} = -\frac{1}{3}. 3. Equation: y=−13xy = -\frac{1}{3}x. Strategic Tip: y/x=−1/3y/x = -1/3. Choice B is incorrect because reciprocal error. Choice C is incorrect because sign error. Choice D is incorrect because reciprocal and sign error.

Key Steps:

•

The correct answer is y=−13xy = -\frac{1}{3}x

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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