I think there is a small mistake/slip/thing on page 131 and page 125 of Edco’s LC Higher Project Maths Papers (namely the sample papers). I’ve noticed it the last two days when two different students needed help with the questions. Although the mistake (IMHO) is not the reason for the their difficulty.

On page 131 students are asked to find the inverse of something like $x^2 + 5$. But students are told the domain is $R$. This function is not bijective and so has no inverse.

On page 125 students are asked to find $p$, $q$, $r$ and $s$ in $px^3 + qx^2 + rx + s$ (or something like this). They are told where the maximum point is and where the inflection point is. Although they should be told too that the inflection point is non-stationary.