(i)[3]
Express $f(x)$ using the form $a(x - b)^2 - c$.
(ii)[1]
State the range for $f$.
(iii)[3]
Find the $x$ values that satisfy $f(x) < 21$.
(iv)[4]
Find the value of the constant $k$ such that the equation $g f(x) = 0$ has two equal roots.
Mathematics 9709 · AS & A Level · Quadratics
Quadratics — practice question
For $x \in \mathbb{R}$, the function $f$ maps $x$ to $2x^2 - 12x + 7$. For the same domain, $g$ maps $x$ to $2x + k$.