№1
→ → →
а {3; -1; 2}; b { -1; -5; -6}; с{ 1; 5; -4}
→ → →
1) а + 3b -2с = ?
→ →
3b{ -3; -15; -18}; -2c{ -2; -10; 8}
→ → →
а + 3b -2с { -2; -26; -8}
→ → → → → →
2) 2b -4(a - c) = 2b -4a +4c=?
→ → →
2b{ -2; -10; -12}; -4а{ -12; 4; -8}; 4с{ 4; 20; -16}
→ → →
2b -4a +4c{-10; 14; -36}
→ → → →→ → → →
3) 2a +3b -a +2b +2a -b = 3a +4b = ?
→ →
3a{9; -3; 6}; 4b{ -4; -20; -24}
→ →
3a +4b {5; -23; -18}
→ →
4) a*b = -3 +5 -12 = -10
→ →
5) |a| = √(9+1 +4) = √14; |b| = √1 + 25 +16) = √42
→ →
|a| + | b| = √14 + √42= √14(1 + √3)