= Solution
At the present epoch, define $s=1+z$ and $F(z)=\dot z/H_0$. For flat matter plus a <cosmological constant>, neglecting radiation,
$$
F(z)=s-E(z),\qquad E(z)=\frac{H(z)}{H_0}=\sqrt{\Omega_{m,0}s^3+\Omega_{\Lambda,0}}.
$$
In an <Einstein-de Sitter universe>, $E=s^{3/2}$, hence
$$
\boxed{F(z)=s-s^{3/2}<0\quad(z>0).}
$$
The <redshift drift> is zero at $z=0$, has initial slope $F'(0)=-1/2$, and decreases monotonically because $F'=1-3\sqrt s/2<0$. Its <second derivative> is $-3/(4\sqrt s)<0$, so the sketch bends downward, with $F\sim-z^{3/2}$ at large positive <redshift>.
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