4.

[tex]4 {x}^{2} + 12x + 11 = 0 \\ a = 4\\ b = 12 \\ c =11 \\ D = {b}^{2} - 4ac = {12}^{2} - 4 \times 4 \times 11 = \\ = 144 - 176 = - 32 \\ D < 0[/tex]

нет решений

5.

1516² - 1516 × 2232 + 1116² = (1516-1116)² = 400² = 160 000