** Still a lot of computation mistakes (sign errors, or just terms disappearing from a line to another), I still didn't take points for little ones but they have to be careful. This emphasizes the importance of writing clearly. **3.3 ex 43 : (ln|u|)' = u'/u not |u'/u|, one should NOT keep the absolute values. **3.3 ex 48 : some people differentiate (x^cos(x)) as sin(x) x^(cos(x)-1), there is confusion on this kind of functions also people tries logarithmic differentiation using ln(a+b)=ln(a)+ln(b) ... ***3.3 ex 56 : Sign errors, often people forget that (ln(1-x))' = -1/(1-x) and likewise (ln(1+5x))' = 5/(1+x) ***3.5 ex 40 : VERY IMPORTANT : My bad on this one, in my head they asked for arctan(tan(x)) in which case is different from the identity function, so I wrote that some people were wrong when they weren't, I remarked everything with the right function in mind though. ***4.1 ex 16 the identity sin(45deg)s=t is only good at one particular time, so we cannot differentiate this inequality to sin(45deg)ds/dt=dx/dt, that is not true.