exponential and logarithmic graphs question
posted by elle .
hi, i desperately need help solving this question:
Find the values of A and k if the general equation of the graph shown is y=Ae^kx where the graph goes through the points (1,4) and (2,10)
do i solve it using simultaneous equations? because i have attempted this yet failed :/
Try taking logs of both sides first, after multiplying both sides by 1 (to avoid logs of negative numbers).
ln (y) = ln (A) + kx
ln (4) = ln (A) k
ln (10) = ln (A) 2k
k = ln 10  ln 4 = 0.91629
k = 0.91629
ln 4 = ln(A)+0.91629
ln (A) = 0.47000
A = 1.6000
y = 1.6 e^(0.91629 x)
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