Can you think of an example a function where it would not be possible to find this limiting value of slopes of secant lines? Please help ASAP Much appreciated

During a bike challenge riders have to collect various colored ribbons each 1/2 mile they collect a red ribbon each eighth mile they collect a green ribbon and each quarter mile they collect a blue ribbion wich colors of ribion will be collected at the 3/4 markrer

Identify the initial amount a and the growth factor b in the exponential function. a(x)=680*4.3^x

Astock has a 25% probability of increasing by $10 and a 75% probability of decreasing by $5. what is the stocks expected increase or decrease?