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Set 5: Exponential Functions (Intermediate)

Explanation

Answer: A

A graph of y=6(1.5)xy = 6(1.5)^x is shown. At what point does it cross the line y=9y = 9?

Graph with Horizontal Line

A.

(1,9)(1, 9)

✓ Correct
B.

(2,9)(2, 9)

C.

(3,9)(3, 9)

D.

(0,9)(0, 9)

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Solve for when y=9y = 9. 1. Set Equal: 6(1.5)x=96(1.5)^x = 9. 2. Divide: (1.5)x=96=1.5(1.5)^x = \frac{9}{6} = 1.5. 3. Recognize: (1.5)x=1.51(1.5)^x = 1.5^1, so x=1x = 1. 4. Point: (1,9)(1, 9). Strategic Tip: When the result equals the base, x=1x = 1. Choice B is incorrect because at x=2x=2, y=6(1.5)2=13.59y = 6(1.5)^2 = 13.5 \neq 9. Choice C is incorrect because this would give an even larger yy value. Choice D is incorrect because at x=0x=0, y=6y = 6, not 9.

Key Steps:

The correct answer is (1,9)(1, 9)

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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