let algebra-2varlineareq-xpeeq7-2xpeeq3-eeq11-xeqn4 = `!x:complex e:complex.
    (x + e = Cx(&7)) /\
    (Cx(&2) * x + e = Cx(&3))
==>
    (e = Cx(&11) /\ x = Cx(-- (&4)))
`;;