5x( x - y ) + 12x - 12y
= 5x( x - y ) + 12( x - y )
= ( x - y )( 5x + 12 )
x2 + 2xy - 9 + y2
= ( x2 + 2xy + y2 ) - 9
= ( x + y )2 - 32
= ( x + y - 3 )( x + y + 3 )
\(5x\left(x-y\right)+12x-12y\)
\(=5x\left(x-y\right)+12\left(x-y\right)\)
\(=\left(x-y\right)\left(5x+12\right)\)
\(x^2+2xy-9+y^2\)
\(=\left(x^2+2xy+y^2\right)-9\)
\(=\left(x+y\right)^2-3^2\)
\(=\left(x+y-3\right)\left(x+y+3\right)\)
Bài làm
a, \(5x\left(x-y\right)+12x-12y=5x\left(x-y\right)+12\left(x-y\right)=\left(5x+12\right)\left(x-y\right)\)
b, \(x^2+2xy-9+y^2=\left(x+y\right)^2-9=\left(x+y-3\right)\left(x+y+3\right)\)
\(5x\left(x-y\right)+12x-12y\)
\(=5x\left(x-y\right)+12\left(x-y\right)\)
\(=\left(5x+12\right)\left(x-y\right)\)
\(x^2+2xy-9+y^2\)
\(=\left(x^2+2xy+y^2\right)-9\)
\(=\left(x+y\right)^2-3^2\)
\(=\left(x+y-3\right)\left(x+y+3\right)\)
