Find the exponential function that passes through (0,5) and (4, 1/2). Formula is y=Ce^kx
5=Ce^0 >>> C=5
1/2=5e^4k
.1=e^4k
take ln of each side
ln(.1)=4k
k=ln(.1)/4== -0.576
1/2=5e^4k
.1=e^4k
take ln of each side
ln(.1)=4k
k=ln(.1)/4== -0.576