Đổi dấu – (4yx2 + yz2)(z – y2) = (4yx2 + yz2)( y2 – z), ta có thừa số
(y2 – z) chung:
C = (y2 – z)(2x2y – yz) – (4yx2 + yz2)(z – y2) + 6x2z(y2 – z)
= (y2 – z)(2x2y – yz) + (4yx2 + yz2)( y2 – z) + 6x2z(y2 – z)
= (y2 – z)[( 2x2y – yz ) + (4yx2 + yz2) + 6x2z]
= (y2 – z)[ 2x2y + 4yx2 + 6x2z]
= (y2 – z)[ 2xy2 + 4yx2 + 6x2z]
= (y2 – z)[ 2x2(y + 2y + 3z)]
= (y2 – z)[ 2x2(3y + 3z)]
= (y2 – z) 2x2 .3(y + z)
= 6x2(y2 – z)(y + z).
a) 7x2 - 4x
= x ( 7x - 4 )
b) 5x2 - 2x + 10 xy - 4y
= x ( 5x - 2 ) + 2y ( 5x - 2 )
= ( x + 2y ) ( 5x - 2 )
a, 7x2-4x=x.(7x-4)
b,5x2-2x+10xy-4y=5x.(x+2y)-2.(x+2y)=(x+2y)(5x-2)
c, x2-4y2+6x+9=(x+3)2-4y2=(x+3-4y)(x+3+4y)
k cho mình nhá
Ta có : 7x2 - 4x = x(7x - 4)
Ta có : 5x2 - 2x + 10xy - 4y
= 5x2 + 10xy - 2x - 4y
= 5x(x + 2y) - 2(x + 2y)
= (x + 2y)(5x - 2)