Question

f(x)=20e^-kx. Find k so that the graph of f passes through point (3,50)

Answer 1

If the graph passes through (3, 50), then x = 3 and y=50.

Let's substitute these two values, you get

50 = 20e^(-3k)
Divide both sides by 20, you get

2.5 = e^(-3k)

Take the log (or ln) of both sides, you get

ln (2.5) = -3k
k = ln(2.5)/-3

You can use the calculator to simplify that to k = -3.05430244

Answer 2

But the EXACT value for k -s ln(2.5)/-3

Answer 3

Okay! Thank you so much!