Răspuns:
1.
[tex]2 \times - 4 - 4 \times 2 + 4 \times - 4 + 20 = - 12 \\ b)x(y - 4) - 4(y - 4) + 4 \\ (x - 4)(y - 4) + 4 \\ 3x - 4x + 12 + 20 = 4 \\ - x = 28 \\ x = - 28 \\ [/tex]
2.
[tex]4 \times 1 \times 3 - 2 \times 1 + 6 \times 3 = 28 \\ 4 \times 28 \times - 2 + 2 \times 28 + 6 \times - 2 = - 180 \\ 4 {x}^{2} - 2x + 6x = 0 \\ 4 {x}^{2} + 4x = 0 \\ {x}^{2} + x = 0 \\ x(x + 1) = 0 \\ x1 = 0 \\ x2 = - 1[/tex]
