\(9x^2+6xy+y^2-25\)
\(=\left(3x+y\right)^2-25\)
\(=\left(3x+y-5\right)\left(3x+y+5\right)\)
\(9x^2+6xy+y^2-25=\left(3x+y\right)^2-25=\left(3x+y-5\right)\left(3x+y+5\right)\)
9x2+6xy+y2-25= (3x)2+2.3x.y+y2 -25
= (3x+y)2-52
= (3x+y-5).(3x+y+5)
Học tốt!
9x2 + 6xy + y2 - 25 = ( 3x )2 + 2 . 3x . y + y2 - 25
= ( 3x + y )2 - 52
= ( 3x + y - 5 ) ( 3x + y + 5 )
