Express $y = 5 - 12x - 3x^2$ in the form $y = a(x + b)^2 + c$ and hence show that $y$ can neve

Question

Express $y = 5 - 12x - 3x^2$ in the form $y = a(x + b)^2 + c$ and hence show that $y$ can never be greater than $20$.[3] Explain why there are no values of $k$ for which the curve $y = (k - 1)x^2 + 2(k + 2)x + k + 3$ is always positive.[4]

Accepted Answer

(a) $y=-3(x+2)^2+17$, hence $y\leq17<20$ (b) No values of $k$.

Quadratic Functions, Equations and Inequalities - Completing the Square and Vertex Form

Quadratic Functions, Equations and Inequalities - Completing the Square and Vertex Form

Solution:

Solution locked