1. The problem statement, all variables and given/known data Given that c= 3i + 4j and d= i - 2j find μ when μc + d is parallel to i +3j 2. Relevant equations 3. The attempt at a solution 3iμ + 4jμ + i + j i( 3μ + 1) + (4μ -2) j since it is parallel to i + 3j therefore 3μ+1=3(4μ-2) giving μ = 7/9 However μ = -1 Additional information: Apparently (see bold) I am supposed to multiply the LHS by 3 instead of the RHS but by equating I and J vectors and looking at the parallel line it would seem logical to do it the way I have (or am I being retarded?). I can accept that I have the multiply LHS instead of RHS but I don't understand why!!