Following is a statement of a theorem about certain cubic equations. For this
theorem, \(b\) represents a real number. Theorem \(\mathbf{A}\). If \(f\) is a cubic
function of the form \(f(x)=x^{3}-x+b\) and \(b>1,\) then the function \(f\) has
exactly one \(x\) -intercept.
Following is another theorem about \(x\) -intercepts of functions: Theorem
\(\mathbf{B}\). If \(f\) and \(g\) are functions with \(g(x)=k \cdot f(x),\) where \(k\)
is a nonzero real number, then \(f\) and \(g\) have exactly the same \(x\)
-intercepts. Using only these two theorems and some simple algebraic
manipulations, what can be concluded about the functions given by the
following formulas?
(a) \(f(x)=x^{3}-x+7\)
(b) \(g(x)=x^{3}+x+7\)
(c) \(h(x)=-x^{3}+x-5\)
(d) \(k(x)=2 x^{3}+2 x+3\)
(e) \(r(x)=x^{4}-x+11\)
(f) \(F(x)=2 x^{3}-2 x+7\)