Answers

2014-03-07T20:21:16+05:30
First multiply the inner brackets

(1-a)(1-b) = 1 - a - b + ab

then square it 

(1 - a - b + ab)^2

= 1 + a² + b² + a²b² - 2a - 2b + 2ab + ab - a²b - b²a

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