Question

Tìm x biết :

\(x^2-2x-6=0\)

 

Answer 1

\(x^2-2x-6=0\)

\(\Leftrightarrow x^2-2x+1-7=0\)

\(\Leftrightarrow\left(x-1\right)^2=7\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}x-1=\sqrt{7}\\x-1=-\sqrt{7}\end{array}\right.\Leftrightarrow\left[\begin{array}{nghiempt}x=\sqrt{7}+1\\x=1-\sqrt{7}\end{array}\right.\)

Vậy ........................................................

 

Answer 2

x^2-2x-6=0

=>(x-1)^2=7

th1

x-1=\(\sqrt{7}\)=>x=\(\sqrt{7+1}\)

th2

x-1=-\(\sqrt{7}\)=>x=-\(\sqrt{7+1}\)

vậy ...