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Find the value for the constant $a$.
Mathematics 9709 · AS & A Level · Series
Series — practice question
The coefficient of $x^3$ in the expansion of $(3 + 2ax)^5$ is six times as large as the coefficient of $x^2$ in the expansion of $(2 + ax)^6$.
Worked solution & mark scheme
This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Obtain the coefficient of $x^3$ in $(3+2ax)^5$ as $10\times 9\times 8a^3=720a^3$” …
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