0 is that working out for us hopefully it's working out oh the minus -1 - there's a minus sign lost somewhere minus 2 here minus 2 theta so I have a minus over here and so then we have 8 equals 10 theta so theta equals 0.8 so we've got the three places where derivative equals 0 0 1 and 0.8 and this is of course the one we want we can verify this by plotting or we can verify by taking the second derivative at that spot and seeing that it's a negative second derivative which gives us that shape now this math was kind of ok we