Mathematics 9709 · AS & A Level · Series

Series — practice question

(main)[5]

In $(a + x)^5 + (1 - 2x)^6$, the coefficient of $x^3$ equals $90$, with $a$ positive. Find the value of $a$.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “For $(a+x)^5$, the coefficient of $x^3$ is $10a^2$.” …

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