How is this algebra working? how did they manage to come up with these formulas? and how do draw and explain the diagram !

v > 1, a 8+1. Divergent oscillation a 1, what will be the path of Y? Combining the 3 given equations, we get: Y: = b + th + (a. U)Yt_1 Yr=13.+(iI:)Yr1 Given the initial value of income, the solution is: _ t b Yt=(::) +1a To determine this, we must consider the parameter values which imply that (E) is positive, negative, greater than 1 or less than -1. Thereare four cases to consider: 1. Monotonic growth where v > 1 and a a + 1