I think the answer is contained in Decartes' rule for polynomial zeroes.
As for first question, if the power of equation winding sown to a constant is n,
there are n possible vaues of x where the equatin is zerol (the roots)
look at equation, it changes sign four times,
that means there are either four real positive roots, or 4-2, or 4-4
that is number of positive roots equal 4, or 2, or zero
(the number of sign changes in equation or that number reduced by even integer).
now change all x to (-x) and substitute into equation and
count number of sign changes term to term. I count one. That
means there is definitely a negative real root since no even integer
subtracted from 1 provide answer greater than zero.