a (1;0)

b(0;-1)

a) 2a (2×1;2×0) = (2;0)

б) - 1/3 b (0 × (-1/3) ; -1 × ( -1/3)) = (0; 1/3)

в) а + b ( 1 + 0 ; 0 - 1 ) = ( 1 ; - 1 )

г) - b ( 0 ; 1 )

a - b ( 1 + 0 ; 0 + 1 ) = ( 1 ; 1 )

д) 3a (3×1 ; 3×0) = (3 ; 0)

4b (4×0 ; -1×4) = (0 ; -4)

3a + 4b = (3+0 ; 0-4) = (3 ; -4)

е)

[tex] |3a + 4b| = \sqrt{3 {}^{2} + ( - 4) {}^{2} } = \\ \sqrt{9 + 16} = \sqrt{25} = 5[/tex]