志强问题2

Clear["Global`*"] (*Clear all variables*)
x0 = 1
替换表
x0 = 1
x2 = x1^2 - x0 - a1 x1
x3 = x1 x2 - x1 - a2 x2
x4 = x1 x3 - x2 - a3 x3
x3 = x1x4 - a4 x4

计算x2x2