Question 8**+Two displacement vectors are represented by \\(3+2i\\) and \\(-1+5i\\). Find the combined displacement.
Question 17****+Find all real \\(t\\) such that \\((t+1)+(2t)i\\) added to \\((3-t)+(t^2-4)i\\) is real.
Question 18*****A learner adds \\((2+3i)+(4+5i)\\) and gets \\(6+15i\\). Diagnose the mistake and correct it.