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Mathematics

Simplify the following:

(a+1a)2+(a1a)2\Big(a + \dfrac{1}{a}\Big)^2 + \Big(a - \dfrac{1}{a}\Big)^2

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Answer

(a+1a)2+(a1a)2=[(a)2+2(a)(1a)+(1a)2]+[(a)22(a)(1a)+(1a)2]=[a2+2+1a2]+[a22+1a2]=2a2+2a2=2(a2+1a2)\Big(a + \dfrac{1}{a}\Big)^2 + \Big(a - \dfrac{1}{a}\Big)^2 = \Big[\Big(a\Big)^2 + 2\Big(a\Big)\Big(\dfrac{1}{a}\Big) + \Big(\dfrac{1}{a}\Big)^2 \Big] + \Big[\Big(a\Big)^2 - 2\Big(a\Big)\Big(\dfrac{1}{a}\Big) + \Big(\dfrac{1}{a}\Big)^2\Big] \\[1em] = \Big[a^2 + 2 + \dfrac{1}{a^2} \Big] + \Big[a^2 - 2 + \dfrac{1}{a^2} \Big] \\[1em] = 2a^2 + \dfrac{2}{a^2} \\[1em] = 2\Big(a^2 + \dfrac{1}{a^2}\Big)

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