For this question, I already have the correct answer of t = 3. My question is, do we ignore because the number can only be 0 where lies on the -axis?
Q. If & & if is on the -axis, find the value of the scalar t.
Your error is that you shouldn't set equal to the zero vector (in fact this has no solutions). All you need to do is set the -component to zero so that lies on the j-axis.
We ignore the j-component, and obtain the equation