Răspuns :
4x la a doua + 8x = -4
4x² + 8x = -4 ⇔ 4x² + 8x + 4 = 0 |:4 ⇔ x² + 2x + 1 = 0 ⇔
⇔ (x + 1)² = 0 ⇔ x₁ = x₂ = -1
S = {-1}
[tex]\displaystyle 4x^2 + 8x = -4 \\ 4x^2+8x+4=0 \\ \\ \boxed{\Delta=b^2-4ac } \\ \\ \Delta=8^2-4\cdot4\cdot4 \\ \Delta=64-64 \\ \Delta=0 \\ \\ X_1=X_2= \frac{-b}{2a} = \frac{-8}{2\cdot4}= \frac{-8}{8}=-1 [/tex]