Question

Help me answer this question..(lesson name expansions)..
Question no 4

Answer 1

$(x+1/3x)^2=x^2+1/9x^2+2*x*1/3x\\(x+1/3x)^2=25/36 + 2/3=49/36\\(x+1/3x)^2=(7/6)^2\\x+1/3x=7/6\\CubingBothSide\\(x+1/3x)^3=(7/6)^3\\x^3+(1/3x)^3+3*x*1/3x(x+1/3x)=343/216\\x^3+1/27x^3+7/6=343/216\\x^3+1/27x^3=343/216-7/6=91/216\\x^3+1/27x^3=91/216$Answer:

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