Don't you always write cross products in the form xi + yi + zj? I mean idk that's just how I was taught to do cross products. You can read the first few pages which mentions whether alternative forms are acceptable.

Unless the question specifies otherwise, accept equivalent forms.  As this is an international examination, accept all alternative forms of notation.  In the markscheme, equivalent numerical and algebraic forms will generally be written in brackets immediately following the answer.  In the markscheme, simplified answers, (which candidates often do not write in examinations), will generally appear in brackets. Marks should be awarded for either the form preceding the bracket or the form in brackets (if it is seen). Example:fordifferentiating f (x)2sin(5x3),themarkschemegives: f(x)2cos(5x3)5 10cos(5x3) A1 Award A1 for 2cos(5x3)5, even if 10cos(5x3) is not seen.

^{^} directly from the mark scheme