#### Topic: User defined trendline exponential decay

Ahoy.

I want to add a trend line for my points which follow a exponential decay. However, I'd rather have the trend line written as something like f(x)=b*exp(k*x) than the standard f(x)=b*a^x.

But writing the model like this $b*exp($k*x) I get the error 87 no solution found.

What am I doing wrong?