Question

tìm x biết: (x-3)*(x+3)-(x-3)^2=0

 

Answer 1

\(\left(x-3\right)\left(x+3\right)-\left(x-3\right)^2=0\Leftrightarrow\left(x-3\right)\left(x+3-x+3\right)=0\Leftrightarrow6\left(x-3\right)=0\Leftrightarrow x-3=0\Leftrightarrow x=3\)

Answer 2

Ta có: \(\left(x-3\right)\left(x+3\right)-\left(x-3\right)^2=0\)

\(\Leftrightarrow x^2-9-x^2+6x-9=0\)

\(\Leftrightarrow6x=18\)

hay x=3