Hi
This is the question I'm trying to do (question 13) 1st attachment
and here are my workings 2nd attachment
I get t= 2 and t=-2/7. As it's time -2/7 isn't reasonable. The answer in the book is t= 2 and t = 2/7.
What have I not understood?
Also, given the answers in the book, I've looked at part d and i get k > 0 for both values of t. Again, any help would be much appreciated.