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Answer:
y = -6x +9
y = 9·(1/3)^x
Step-by-step explanation:
In each case, the y-intercept is 9.
Linear
The slope is rise/run = (3-9)/(1-0) = -6, so the equation is ...
y = mx + b . . . . . . . slope m, intercept b
y = -6x +9
Exponential
The ratio of value at x=1 to that at x=0 is 3/9 = 1/3. That is the "growth factor," so the equation is ...
y = 9·(1/3)^x
