(a)[2]
Write $4x^2 + 10x + 6$ in the form $a(x+b)^2 + c$, where $a$, $b$ and $c$ are rational constants that must be found.
(b)[1]
The curve with equation $y = 4x^2 + 10x + 6$ and the line $y = k$ intersect at exactly one point. Using your answer to part (a), or by another method, state the value of the constant $k$.