3

Set 12: Exponential Functions

Explanation

Answer: A

The graph of an exponential function has points (1,6)(1, 6) and (3,54)(3, 54). What is the equation?

A.

y=2(3)xy = 2(3)^x

✓ Correct
B.

y=6(3)xy = 6(3)^x

C.

y=3(2)xy = 3(2)^x

D.

y=54(6)xy = 54(6)^x

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Use the two points to find aa and bb. 1. Point 1: 6=a(b)1=ab6= a(b)^1 = ab. 2. Point 2: 54=a(b)3=ab354= a(b)^3 = ab^3. 3. Divide: 546=ab3ab=b2=9\frac{54}{6} = \frac{ab^3}{ab} = b^2 = 9, so b=3b = 3. 4. Find aa: a(3)=6a(3) = 6, so a=2a = 2. 5. Equation: y=2(3)xy = 2(3)^x. Strategic Tip: Dividing equations eliminates aa and isolates a power of bb. Choice B is incorrect because a=2a = 2, not 6. Choice C is incorrect because b=3b = 3, not 2. Choice D is incorrect because neither value is correct.

Key Steps:

The correct answer is y=2(3)xy = 2(3)^x

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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