Question

X^2 + 2x + 7=0.
Rezolvați ecuația pls. Dau coroana .

Answer 1

Ecuatie de forma    ax²+bx+c =0   unde a=1 , b=2, c=7 

  Δ=b²-4ac    Δ=2²-4.1.7=4-28=-24 negativ
   deci ecuatia nu are solutii reale .
 

Answer 2

[tex]\it x^2+2x+7=0 \Rightarrow x^2+2x+1+6 = 0 \Rightarrow (x+1)^2 +6 = 0 \Rightarrow \\\;\\ \Rightarrow (x+1)^2 - i^2\cdot6 = 0 \Rightarrow (x+1)^2 - (i\sqrt{6})^2 = 0 \Rightarrow \\\;\\ \Rightarrow (x+1-i\sqrt6)(x+1+i\sqrt6)=0 \Rightarrow \begin{cases} \it x+1-i\sqrt6=0 \\\;\\ \it x+1+i\sqrt6=0\end{cases} \Rightarrow \\\;\\ \\\;\\ \Rightarrow \begin{cases} \it x_1 = -1 + i\sqrt6 \\\;\\ \it x_2 = -1 - i\sqrt6\end{cases}[/tex]