(a) The curve $y= f (x)$ has a horizontal asymptote $y=k$ and cuts the axes at $(a, 0)$ and $(0, b)$, where $a$, $b$ and $k$ are non-zero constants. It is given that $f ^{-1}(x)$ exists. State, if possible, the coordinates of the points where the following curves cut the axes and the equations of their asymptotes.
(i) $y= f (2 x-3)$
(ii) $y= f ^{-1}(x)$
[2]
(b) The function $g$ is given by $g : x \mapsto ln \left(\frac{ e ^x+5}{ e ^x-1}\right), \text {, for } x \in \mathbb{R} , x>0$.
(i) Find $g ^{-1}(x)$ and state its domain.
[3]
The function $h$ is defined by
$h : x \mapsto 1+\sqrt{9-(x-2)^2} \text {, for } x \in \mathbb{R} , -1 \leq x \leq 5 .$
(ii) Find the exact solutions of $g ^{2021} h (x)=ln 2$, giving your answer in its simplest form.
[3]
(a)(i) $(a, 0) \rightarrow\left(\frac{a+3}{2}, 0\right) \quad(0, b) \rightarrow\left(\frac{3}{2}, b\right) \left(\frac{a+3}{2}, 0\right)$ is the only point. Asymptote: $y=k$
(ii) $(a, 0) \rightarrow(0, a), (0, b) \rightarrow(b, 0)$ Asymptote: $x=k$
(b)(i) $ \mathrm{g}^{-1}(x)=\ln \left(\frac{\mathrm{e}^x+5}{\mathrm{e}^x-1}\right), \mathrm{D}_{\mathrm{g}^{-1}}=\mathrm{R}_{\mathrm{g}}=(0, \infty)$ (ii) $x=2 \pm \sqrt{(2+\ln 7)(4-\ln 7)}$
(a)(i) $(a, 0) \rightarrow\left(\frac{a+3}{2}, 0\right) \quad(0, b) \rightarrow\left(\frac{3}{2}, b\right)$
$\left(\frac{a+3}{2}, 0\right)$ is the only point. Asymptote: $y=k$
(ii) $(a, 0) \rightarrow(0, a), (0, b) \rightarrow(b, 0)$
Asymptote: $x=k$
(b)(i) $y=\ln \left(\frac{\mathrm{e}^x+5}{\mathrm{e}^x-1}\right) \Rightarrow \mathrm{e}^y=\frac{\mathrm{e}^x+5}{\mathrm{e}^x-1} \Rightarrow\left(\mathrm{e}^y-1\right) \mathrm{e}^x=\mathrm{e}^y+5$
$\Rightarrow \mathrm{e}^x=\frac{\mathrm{e}^y+5}{\mathrm{e}^y-1} \Rightarrow x=\ln \left(\frac{\mathrm{e}^y+5}{\mathrm{e}^y-1}\right)$
$\therefore \mathrm{g}^{-1}(x)=\ln \left(\frac{\mathrm{e}^x+5}{\mathrm{e}^x-1}\right)$
$\mathrm{D}_{\mathrm{g}^{-1}}=\mathrm{R}_{\mathrm{g}}=(0, \infty)$
(ii) Note: $\mathrm{g}$ is a self-inverse function
$\mathrm{g}^{2021} \mathrm{~h}(x)=\ln 2$
$\operatorname{gh}(x)=\ln 2$
$h(x)=g^{-1}(\ln 2)=\ln 7$
$1+\sqrt{9-(x-2)^2}=\ln 7$
$9-(x-2)^2=(\ln 7-1)^2$
$(x-2)^2=9-(\ln 7-1)^2=(2+\ln 7)(4-\ln 7)$
$x=2 \pm \sqrt{(2+\ln 7)(4-\ln 7)}$