Compute the following:
(i)[ab−ba]+[abba]
(ii)[a2+b2b2+c2a2+c2a2+b2]+[2ab2bc−2ac−2ab]
(iii)⎡⎢⎣−14−68516285⎤⎥⎦+⎡⎢⎣1276805324⎤⎥⎦
(iv)[cos2xsin2xsin2xcos2x]+[sin2xcos2xcos2xsin2x]
[ab−ba]+[abba]=[a+ab+b−b+ba+a]=[2a2b02a]
[a2+b2b2+c2a2+c2a2+b2]+[2ab2bc−2ac−2ab]=[a2+b2+2abb2+c2+2aba2+c2−2aca2+b2−2ab]=[(a+b)2(b+c)2(a−c)2(a−b)2][∵(a+b)2=a2+2ab+b2(a−b)2=a2−2ab+b2]
⎡⎢⎣−14−68516285⎤⎥⎦+⎡⎢⎣1276805324⎤⎥⎦=⎡⎢⎣−1+124+7−6+68+85+1016+52+38+25+4⎤⎥⎦=⎡⎢⎣11110165215109⎤⎥⎦
[cos2xsin2xsin2xcos2x]+[sin2xcos2xcos2xsin2x]=[cos2x+sin2xsin2x+cos2xsin2x+cos2xcos2x+sin2x]=[1111][∵sin2x+cos2x=1]