[tex]\displaystyle x(x-5)=3x-7 \\ x^2-5x=3x-7 \\ x^2-5x-3x+7 \\ x^2-8x+7=0 \\ \\ \text{Ecuatie de grad 2 , aplicam delta.} \\ \\ \Delta=b^2-
4ac \\ \Delta=(-8)^2-4 \cdot 1 \cdot 7 \\ \Delta=64-28 \\ \Delta=36 \\ \\ X_{1,2}= \frac{-b\pm \sqrt{\Delta} }{2a} \\ \\ \\X_1= \frac{8-6}{2}=1 \\ \\ X_2= \frac{8+6}{2} = 7 \\ \\ \\ S=\{1;7\}[/tex]
