Write down the first three terms in the expansion, in descending powers of $x$, of \({{\left( 2x-\

Question

Write down the first three terms in the expansion, in descending powers of $x$, of ${{\left( 2x-\frac{1}{x} \right)}^{7}}$.[3] Find the value of $a$ if the coefficient of ${{x}^{5}}$ in the expansion of $\left( 1+a{{x}^{2}} \right){{\left( 2x-\frac{1}{x} \right)}^{7}}$ is $224$.[3]

Accepted Answer

(i) $128x^7-448x^5+672x^3$ (ii) $a=1$

2016 NGHS AM P1 Q4

2016 NGHS AM P1 Q4

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