Methods2024 NHT Exam 2 Section A · Q9CAS active1 mark

Values of a for which a quadratic is always positive

Let $f(x) = 3x^2 - 2ax + 6$ , where $a \in R$ .

The set of values of $a$ such that $f(x) > 0$ for all $x \in R$ is

1 mark

\left\{a : a \geq 3\sqrt{2}\right\}

\left\{a : a < -3\sqrt{2}\right\} \cup \left\{a : a > 3\sqrt{2}\right\}

\left\{a : a \leq -3\sqrt{2}\right\} \cup \left\{a : a \geq 3\sqrt{2}\right\}

\left\{a : -3\sqrt{2} < a < 3\sqrt{2}\right\}

\left\{a : -3\sqrt{2} \leq a \leq 3\sqrt{2}\right\}

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