Mathematics 9709 · AS & A Level · Trigonometry

Trigonometry — practice question

The polynomial $p(x)$ is given by $p(x) = ax^3 + bx^2 - ax - 24$, where $a$ and $b$ are constants. It is stated that $(2x - 3)$ is a factor of $p(x)$ and that, when $p(x)$ is divided by $(x + 1)$, the remainder is $-15$.
(a)[4]

Determine the values of $a$ and $b$.

(b)[3]

Therefore factorise $p(x)$ fully.

(c)[2]

Hence solve the equation $p(3\cosec \theta) = 0$ for $90^\circ < \theta < 270^\circ$.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Put $x=\dfrac{3}{2}$ and set the expression equal to $0$, and put $x=-1$ and set it equal to $-15$

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