a, 5x^2y -20xy+20y b,x^2-4x -9y^2+12y c,,25x^2 +10x-4y^2+1 d,4x^2-19x+12 03/11/2021 Bởi Melody a, 5x^2y -20xy+20y b,x^2-4x -9y^2+12y c,,25x^2 +10x-4y^2+1 d,4x^2-19x+12
a/ $5x²y-20xy+20y\\=5y(x²-4x+4)\\=5y(x-2)²$ b/ $x²-4x-9y²+12y\\=(x-3y)(x+3y)-4(x-3y)\\=(x-3y)(x+3y-4)$ c/ $25x²+10x-4y²+1\\=(5x+1)²-4y²\\=(5x+1-2y)(5x+1+2y)$ d/ $4x²-19x+12\\=4x²-16x-3x+12\\=4x(x-4)-3(x-4)\\=(4x-3)(x-4)$ Bình luận
`a) 5x^2 y-20xy+20y` `=5y(x^2-4x+4)` `=5y(x-2)^2` `b) x^2-4x-9y^2+12y` `=(x^2-4x+4)-(9y^2-12y+4)` `=(x-2)^2-(3y-2)^2` `=(x-2-3y+2)(x-2+3y-2)` `=(x-3y)(x+3y-4)` `c) 25x^2+10x-4y^2+1` `=(25x^2+10x+1)-4y^2` `=(5x+1)^2-(2y)^2` `=(5x-2y+1)(5x+2y+1)` `d) 4x^2-19x+12` `=4x^2-16x-3x+12` `=4x(x-4)-3(x-4)` `=(x-4)(4x-3)` Bình luận
a/ $5x²y-20xy+20y\\=5y(x²-4x+4)\\=5y(x-2)²$
b/ $x²-4x-9y²+12y\\=(x-3y)(x+3y)-4(x-3y)\\=(x-3y)(x+3y-4)$
c/ $25x²+10x-4y²+1\\=(5x+1)²-4y²\\=(5x+1-2y)(5x+1+2y)$
d/ $4x²-19x+12\\=4x²-16x-3x+12\\=4x(x-4)-3(x-4)\\=(4x-3)(x-4)$
`a) 5x^2 y-20xy+20y`
`=5y(x^2-4x+4)`
`=5y(x-2)^2`
`b) x^2-4x-9y^2+12y`
`=(x^2-4x+4)-(9y^2-12y+4)`
`=(x-2)^2-(3y-2)^2`
`=(x-2-3y+2)(x-2+3y-2)`
`=(x-3y)(x+3y-4)`
`c) 25x^2+10x-4y^2+1`
`=(25x^2+10x+1)-4y^2`
`=(5x+1)^2-(2y)^2`
`=(5x-2y+1)(5x+2y+1)`
`d) 4x^2-19x+12`
`=4x^2-16x-3x+12`
`=4x(x-4)-3(x-4)`
`=(x-4)(4x-3)`