InterviewSolution
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    				| 1. | 
                                    सिद्ध करें कि `(vec(a)-vec(b))xx(vec(a)+vec(b))=2(vec(a)xxvec(b))`. | 
                            
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Answer» `L.H.S.=(vec(a)-vec(b))xx(vec(a)+vec(b))` `=vec(a)xxvec(a)+vec(a)xxvec(b)-vec(b)xxvec(a)-vec(b)xxvec(b)" "["वितरण नियम से"]` `=vec(a)xxvec(b)-vec(b)xxvec(a)" "[because vec(a)xxvec(a)=vec(0)" तथा "vec(b)xxvec(b)=vec(0)]` `=(vec(a)xxvec(b))+(vec(a)xxvec(b))" "[because-(vec(b)xxvec(a))=(vec(a)xxvec(b))]` `=2(vec(a)xxvec(b))`.  | 
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