Question

Answer 1

\(x^2-8x+15=0\\ \Leftrightarrow x^2-5x-3x+15=0\\ \Leftrightarrow x\left(x-5\right)-3\left(x-5\right)=0\\ \Leftrightarrow\left(x-3\right)\left(x-5\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=3\\x=5\end{matrix}\right.\)

Answer 2

=>(x-5)(x-3)=0

=>x=5 hoặc x=3

Answer 3

\(x^2-3x-5x+15=0\)

\(\left(x-3\right)\left(x-5\right)\)\

=> x \(\in\) { 3:5}

Answer 4

\

=> x  { 3:5 }