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Show that the coefficient of $x^2$ is zero.
Mathematics 9709 · AS & A Level · Series
Series — practice question
For the expansion of $(1 - \frac{2x}{a})(a + x)^5$, where $a$ is a non-zero constant, show that the coefficient of $x^2$ is zero.
Worked solution & mark scheme
This 3-mark question has a full step-by-step worked solution and mark scheme. One marking point: “From the binomial expansion $(a+x)^5 = a^5 + 5Ca^4x + 5Ca^3x^2 + \dots$” …
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