10

Set 13: Linear Functions (Intermediate)

Explanation

Answer: A

Which equation represents a line with a slope of 12\frac{1}{2} and a y-intercept of 4-4?

A.

y=12x4y = \frac{1}{2}x - 4

✓ Correct
B.

y=4x+12y = -4x + \frac{1}{2}

C.

y=2x4y = 2x - 4

D.

y=12x+4y = \frac{1}{2}x + 4

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Substitute mm and bb into y=mx+by = mx + b. 1. Given: m=12m = \frac{1}{2}, b=4b = -4. 2. Substitute: y=(12)x+(4)y = (\frac{1}{2})x + (-4). 3. Simplify: y=12x4y = \frac{1}{2}x - 4. Strategic Tip: Direct substitution into the slope-intercept form is the fastest way to write the equation. Choice B is incorrect because it swaps the slope and y-intercept. Choice C is incorrect because it uses the reciprocal of the slope. Choice D is incorrect because it has the wrong sign for the y-intercept.

Key Steps:

The correct answer is y=12x4y = \frac{1}{2}x - 4

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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