Mathematics 9709 · AS & A Level · Logarithmic and exponential functions

Logarithmic and exponential functions — practice question

The polynomial $p(x)$ is defined as $p(x) = ax^3 - 11x^2 - 19x - a$, where $a$ is a constant. It is known that $(x - 3)$ is a factor of $p(x)$.
(a)[2]

Determine the value of $a$.

(b)[3]

With this value of $a$, factorise $p(x)$ completely.

(c)[4]

Hence find the exact values of $y$ for which $p(e^{y} + e^{-y}) = 0$.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Put in $x=3$, set the expression to zero and try to solve

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