6

Set 11: Exponential Functions (Intermediate)

Explanation

Answer: A

Which equation best models the data in the table?

xy
05
115
245

Exponential Growth Data

A.

y=5(3)xy = 5(3)^x

✓ Correct
B.

y=3(5)xy = 3(5)^x

C.

y=5(1.3)xy = 5(1.3)^x

D.

y=5x+10y = 5x + 10

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Check the initial value and the multiplier ratio. 1. Initial Value: When x=0x=0, y=5y=5. So a=5a=5. (Eliminates B). 2. Check Ratio: From x=0x=0 to x=1x=1, yy goes 5155\to 15 (×3 \times 3). From x=1x=1 to x=2x=2, yy goes 154515\to 45 (×3 \times 3). 3. Determine Factor: The constant multiplier is 3, so b=3b=3. 4. Form Equation: y=5(3)xy = 5(3)^x. Strategic Tip: Divide consecutive yy-values (y2/y1y_2 / y_1) to find the growth factor bb. Choice B is incorrect because it has the wrong initial value (3 instead of 5). Choice C is incorrect because 1.33 is not the correct multiplier. Choice D is incorrect because the growth is not linear (add 10, then add 30).

Key Steps:

The correct answer is y=5(3)xy = 5(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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