Câu 1:
a, $(5x+1)(2x-y)$
$=10x²-5xy+2x-y$
b, $(2x+y)²$
$=4x²+4xy+y²$
Câu 2:
a, $7(x-y)+x(x-y)$
$=(x-y)(7+x)$
b, $2xy+3z+6y+xz$
$=2y(x+3)+z(x+3)$
$=(x+3)(2y+z$
c, $3x²+6xy+3y²-3z²$
$=3[(x+y)²-z²]$
$=3(x+y-z).(x+y+z)$
d, $x²-7x+10$
$=x²-5x-2x+10$
$=(x-5)(x-2)$
Câu 3:
a, $3x(x²-16)=0$
$⇔\left[ \begin{array}{l}x=0\\x²-16=0\end{array} \right.$
$⇔\left[ \begin{array}{l}x=0\\x=±4\end{array} \right.$
b, $(2x+3)²-(x-1)²=0$
$⇔(2x+3-x+1)(2x+3+x-1)=0$
$⇔(x+4).(3x+2)=0$
$⇔\left[ \begin{array}{l}x+4=0\\3x+2=0\end{array} \right.$
$⇔\left[ \begin{array}{l}x=-4\\x=-2/3\end{array} \right.$
c, $2x²-x-6=0$
$⇔2x²-4x+3x-6=0$
$⇔(x-2)(2x+3)=0$
$⇔\left[ \begin{array}{l}x=2\\x=-3/2\end{array} \right.$
