<PRE><B>Question 1066581</B>
Write an exponential decay function where the y-intercept is 4 and the y-values decrease by one-half as x increases by 1. 
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Form: y = a(b)^x
Because y-values decrease by one-half as x increases by 1
Form:: y = a(1/2)^x 
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Since y-intercept is 4,
4 = a(1/2)^0
a = 4
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Ans: y = 4(1/2)^x
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Cheers,
Stan H.
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