GMAT Problem Solving (PS) | Re: (11+1/11)^2-(11-1/11)^2=?

==> You get \((11+\frac{1}{11})^2-(11-\frac{1}{11})^2=[(11+\frac{1}{11})-(11-\frac{1}{11})][(11+\frac{1}{11})+(11-\frac{1}{11})]= \frac{2}{11}(22)=4.\)

The answer is C.
Answer: C

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