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Mathematics

By using standard formulae, expand the following:

(23x32x1)2\Big(\dfrac{2}{3}x - \dfrac{3}{2x} - 1\Big)^2

Expansions

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Answer

(23x32x1)2=[23x+(32x)+(1)]2=(23x)2+(32x)2+(1)2+2[(23x)(32x)+(32x)(1)+(1)(23x)]=49x2+94x2+1+2[1+32x23x]=49x2+94x2+12+3x43x=49x2+94x21+3x43x\Big(\dfrac{2}{3}x - \dfrac{3}{2x} - 1\Big)^2 = \Big[\dfrac{2}{3}x + \Big(-\dfrac{3}{2x}\Big) + \Big(-1\Big)\Big]^2 \\[1em] = \Big(\dfrac{2}{3}x\Big)^2 + \Big(-\dfrac{3}{2x}\Big)^2 + (-1)^2 + 2 \Big[\Big(\dfrac{2}{3}x\Big)\Big(-\dfrac{3}{2x}\Big) + \Big(-\dfrac{3}{2x}\Big)\Big(-1\Big)+\Big(-1\Big)\Big(\dfrac{2}{3}x\Big) \Big] \\[1em] = \dfrac{4}{9}x^2 + \dfrac{9}{4x^2} + 1 + 2\Big[-1 + \dfrac{3}{2x} - \dfrac{2}{3}x \Big] \\[1em] = \dfrac{4}{9}x^2 + \dfrac{9}{4x^2} + 1 - 2 + \dfrac{3}{x} - \dfrac{4}{3}x \\[1em] = \dfrac{4}{9}x^2 + \dfrac{9}{4x^2} -1 + \dfrac{3}{x} - \dfrac{4}{3}x \\[1em]

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