(i)[3]
Find the set of $x$ values for which $y > 9$.
(ii)[4]
Express $2x^2 - 3x$ as $a(x + b)^2 + c$, where $a$, $b$ and $c$ are constants, and give the coordinates of the vertex of the curve.
(iii)[3]
The functions $f$ and $g$ are defined for every real value of $x$ by $f(x) = 2x^2 - 3x$ and $g(x) = 3x + k$, where $k$ is a constant. Find the value of $k$ for which the equation $gf(x) = 0$ has equal roots.