Set 1: Quadratic Equations

Explanation

Answer: A

A stone is dropped from a bridge 144 ft high. $h(t) = -16t^2 + 144$ . How long until it hits the water?

3 seconds

✓ Correct

9 seconds

4.5 seconds

12 seconds

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Set $h(t) = 0$ . 1. $-16 t^2 + 144 = 0$ . 2. $16t^2 = 144$ . 3. $t^2 = 9$ . 4. $t = 3$ seconds. Choice B is incorrect. Choice C is incorrect. Choice D is incorrect.

Key Steps:

•

The correct answer is 3 seconds

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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