10

Set 15: Linear Functions

Explanation

Answer: A

Find the value of kk if the line through (1,2)(1, 2) and (3,k)(3, k) is perpendicular to y=2xy = 2x.

A.

11

✓ Correct
B.

33

C.

−2-2

D.

66

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Perpendicular slope. 1. Target Slope: Perpendicular to 2 is −1/2-1/2. 2. Line Slope: k−23−1=k−22\frac{k-2}{3-1} = \frac{k-2}{2}. 3. Equate: k−22=−12\frac{k-2}{2} = -\frac{1}{2}. 4. Solve: k−2=−1→k=1k-2 = -1 \rightarrow k = 1. Strategic Tip: Set up the slope formula equal to the target slope. Choice B is incorrect. Choice C is incorrect. Choice D is incorrect.

Key Steps:

•

The correct answer is 11

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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