bạn ơi cái chỗ 21x^2 ? y^2 là dấu cộng hay trừ vậy?

Nó là 1 á

\(-7xy+3x^2+2y^2\\=3x^2-7xy+2y^2\\=3x^2-6xy-xy+2y^2\\=3x(x-2y)-y(x-2y)\\=(x-2y)(3x-y)\)

6x²+7xy+2y²

=6x²+3xy+4xy+2y²

=3x.(2x+y)+2y.(2x+y)

=(2x+y)(3x+2y)

\(=4x^4+21x^2y^2+y^4-25x^2y^2\)

\(\left(2x^2+y^2\right)-\left(5xy\right)^2\)

\(\left(2x^2+y^2-5xy\right)\left(2x^2+y^2+5xy\right)\)

$=4{}^{}+21{}^{}{}^{}+{}^{}-25{}^{}{}^{}$

$\left(2{}^{}+{}^{}\right)-{}^{}$

$\left(2{}^{}+{}^{}-5xy\right)\left(2{}^{}+{}^{}+5xy\right)$

1, \(35x^2-79x-12=35x^2-84x+5x-12\)

\(=5x\left(7x+1\right)-12\left(7x+1\right)=\left(5x-12\right)\left(7x+1\right)\)

2, \(20x^2+45x-24x-54=5x\left(4x+9\right)-6\left(4x+9\right)\)

\(=\left(5x-6\right)\left(4x+9\right)\)

   7xy².(35x²y - 21x³y)
= 245x³y³ - 147x⁴y³
= 49x³y³(5 - 3x)

4x⁴ - 21 x²y² + y⁴ 

= (4x⁴ + 4x²y² + y⁴) - 25x²y² 

=  [(2x²)² + 2x² . 2 . y² + (y²)²] - 25x²y²

= (2x² + y²) - 25x²y² 

= (2x² + y² - 5xy) (2x² + y² + 5xy)

4x⁴ - 21 x²y² + y⁴ 

= (4x⁴ + 4x²y² + y⁴) - 25x²y² 

=  [(2x²)² + 2x² . 2 . y² + (y²)²] - 25x²y²

= (2x² + y²) - 25x²y² 

= (2x² + y² - 5xy) (2x² + y² + 5xy)

phân tích đa thức thành nhân tử

a, 6x^2 + 7xy + 2y^2

=6x^2+3xy+4xy+2y^2

=3x(x+y)+2y(x+y)

=(3x+2y)(x+y)

b, 9x^2 - 9xy - 4y^2

=9x^2 +3xy-12xy-4y^2

=3x(x+y)-4y(x+y)

=(3x+4y)(x+y)

c, x^2 - y^2 + 10x - 6y + 16=x^2-y^2+6x-6y+4x+16=x(x+6)-y(x+6)+4(x+6)=(x-y+4)(x+6)

Bài làm

a, 6x² + 7xy + 2y²

= 6x² + 3xy + 4xy + 2y² 

= ( 6x² + 3xy ) + ( 4xy + 2y² )

= 3x( 2x + y ) + 2y( 2x + y )

= ( 2x + y )( 3x + 2y )

b, 9x² - 9xy - 4y² 

= 9x² - 12xy + 3xy - 4y² 

= ( 9x² - 12xy ) + ( 3xy - 4y² )

= 3x( 3x - 4y ) + y ( 3x - 4y )

= ( 3x + y )( 3x - 4y )

c, x² - y² + 10x - 6y + 16

 = x² - y² - 6x + 6y + 4x + 16

= x( x + 6 ) - y( x + 6 ) + 4( x + 6 )

= ( x - y + 4 )( x + 6 )

# Học tốt #