Question

1.Tìm x

a ) ( x-3). (x+3) - x2 = 2x

b ) (x+4). ( x-1) +x.( x-3) -2x2 = 13

Answer 1

a) 

\(\left(x-3\right)\left(x+3\right)-2x=2x\)

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

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

\(\Leftrightarrow x-3=0\) hoặc \(x+3=0\)

\(\Leftrightarrow x=3\)                  \(x=-3\)