Question

Answer 1

A luôn dương

\(A=\left(-8+6\right)\left(-8-6\right)=-2\left(-14\right)=28\\ =\left(x^2+3\right)\left(x-2\right)\\ =x^2-6xy+9y^2\\ =x^2-16y^2\\ \Leftrightarrow x^2+2x-x^2=6\Leftrightarrow2x=6\Leftrightarrow x=3\\ \Leftrightarrow\left(x-3\right)\left(x+2\right)=0\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)

Answer 2

>0

28

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

\(=x^2-6xy+9y^2\)

\(x^2-16y^2\)

3

\(\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)