phân tích đa thức thành nt a, 3x^2-3y^2-12x+12y b,25-x^2+6xy-9y^2 07/12/2021 Bởi Adalynn phân tích đa thức thành nt a, 3x^2-3y^2-12x+12y b,25-x^2+6xy-9y^2
Hướng dẫn trả lời: `a)3x^2-3y^2-12x+12y.` `=(3x^2-3y^2)-(12x-12y).` `=3.(x^2-y^2)-12.(x-y).` `=3.(x+y).(x-y)-12.(x-y).` `=(x-y).[3.(x+y)-12].` `=(x-y).3.[(x+y)-4].` `=(x-y).3.(x+y-4).` `b)25-x^2+6xy-9y^2.` `=25-(x^2-6xy+9y^2).` `=5^2-[x^2-2.x.3y+(3y)^2].` `=5^2-(x-3y)^2.` `=[5+(x-3y)].[5-(x-3y)].` `=(x-3y+5).(-x+3y+5).` Bình luận
Đáp án: `a) 3x^2-3y^2-12x+12y` `=3(x^2-y^2)-12(x-y)` `=3(x-y)(x+y)-12(x-y)` `=(x-y)(3x+3y-12)` `=3(x-y)(x+y-4)` `b) 25-x^2+6xy-9y^2` `=25-(x^2-6xy+9y^2)` `=5^2-(x-3y)^2` `=(5-x+3y)(5+x-3y)` Bình luận
Hướng dẫn trả lời:
`a)3x^2-3y^2-12x+12y.`
`=(3x^2-3y^2)-(12x-12y).`
`=3.(x^2-y^2)-12.(x-y).`
`=3.(x+y).(x-y)-12.(x-y).`
`=(x-y).[3.(x+y)-12].`
`=(x-y).3.[(x+y)-4].`
`=(x-y).3.(x+y-4).`
`b)25-x^2+6xy-9y^2.`
`=25-(x^2-6xy+9y^2).`
`=5^2-[x^2-2.x.3y+(3y)^2].`
`=5^2-(x-3y)^2.`
`=[5+(x-3y)].[5-(x-3y)].`
`=(x-3y+5).(-x+3y+5).`
Đáp án:
`a) 3x^2-3y^2-12x+12y`
`=3(x^2-y^2)-12(x-y)`
`=3(x-y)(x+y)-12(x-y)`
`=(x-y)(3x+3y-12)`
`=3(x-y)(x+y-4)`
`b) 25-x^2+6xy-9y^2`
`=25-(x^2-6xy+9y^2)`
`=5^2-(x-3y)^2`
`=(5-x+3y)(5+x-3y)`