4. 2AB + 3BC + 2CA = 2AB + 2CA + 3BC = 2( CA + AB) + 3BC =
= 2 CB + 3 BC = 3BC - 2 BC = BC
stim CB = - BC
e. 2AB + BA + 3CA + BC = 2AB - AB + 3AC + BC = AB + BC + 3CA =
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OPUSI BA = - AB
= AC + 3CA = - CA + 3CA = 2CA
AC = - CA
3AB + 5BC -3(AC + CB ) = 3AB +5BC - 3 AB = 5 BC
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AB
1 . 2u + ( v +u ) / 2 - ( v -u ) = ( 4u + v +u - 2v + 2u ) / 2 = (7u - v ) /2
2. 5· ( 2u + v) -3·( 5u -v) = 10u + 5v - 15u + 3v = -5u + 8v
3. 3( u -v) + ( u - 2v ) = 3u - 3v + u -2v = 4u - 5v