Question

Descompuneti in factori: x^2-4x-1

Answer 1

(1) daca aveam forma x^2-4x-1 o rezolvam ca ec. de gradul 2 ... , adica: [tex]\Delta=(-4)^2-4\cdot1\cdot(-1)=20\;\rightarrow\;\sqrt{\Delta}=2\sqrt5\;;\\ x_{1;2}=\frac{4\pm2\sqrt5}{2}\rightarrow\;x_1=2+\sqrt5\;si\;x_2=2-\sqrt5\;;\\ \Rightarrow\;\;x^2-4x-1=(x-2-\sqrt5)(x-2+\sqrt5)[/tex]

Pt.deschidere, apasa tasta F5 ...