6

Set 5: Linear Functions (Advanced)

Explanation

Answer: A

A candle is 12 inches tall and burns at 2 inches per hour. Which equation models height hh after tt hours?

A.

h=−2t+12h = -2t + 12

✓ Correct
B.

h=2t+12h = 2t + 12

C.

h=12t−2h = 12t - 2

D.

h=−2t−12h = -2t - 12

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Burning means decreasing height. 1. Rate: Burns 2 in/hr →\rightarrow Slope −2-2. 2. Start: 12 inches →\rightarrow Intercept +12+12. 3. Equation: h=−2t+12h = -2 t + 12. Strategic Tip: Always check if the quantity is increasing (+) or decreasing (-). Choice B is incorrect because it implies the candle grows. Choice C is incorrect because it swaps rate and start. Choice D is incorrect because it implies negative initial height.

Key Steps:

•

The correct answer is h=−2t+12h = -2t + 12

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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