Дано вектори a(0; –3); b(–2; 1); c = kd + 2b. Знайдіть k, якщо c(–4; 11)
(–4; 11) = k · (0; –3) + 2 · (–2; 1);
(–4; 11) = (0; –3k) + (–4; 2);
(–4; 11) = (–4; –3k + 2);
–3k + 2 = 11;
–3k = 11 – 2;
–3k = 9;
k = –3.