PTĐT THÀNH NHÂN TỬ
8, 3.(x-y) – 5x.(y-x)
9, x.(y-1) + y.(1-y)
10, x^3 – 2x^2 +x
11, 2x^2 + 4x + 2 – 2y^2
12, 2x – 2y – x^2 + 2xy – y^2
13, x^3 + 2x^2y + xy^2 – 9x
PTĐT THÀNH NHÂN TỬ
8, 3.(x-y) – 5x.(y-x)
9, x.(y-1) + y.(1-y)
10, x^3 – 2x^2 +x
11, 2x^2 + 4x + 2 – 2y^2
12, 2x – 2y – x^2 + 2xy – y^2
13, x^3 + 2x^2y + xy^2 – 9x
8/
`3(x-y)-5x(y-x)`
`⇔3(x-y)+5x(x-y)`
`⇔(3+5x)(x-y)`
9/
`x(y-1)+y(1-y)`
`⇔x(y-1)-y(1-y)`
`⇔(x-y)(1-y)`
10/
`x^3-2x^2+x`
`⇔x^3-x^2-x^2+x`
`⇔x^2(x-1)-x(x-1)`
`⇔(x^2-x)(x-1)`
`⇔x(x-1)^2`
11/
`2x^2+4x+2-2y^2`
`⇔2(x^2+2x+1-y^2)`
`⇔2[(x+1)^2-y^2]`
`⇔2(x+1-y)(x+1+y)`
12/
`2x-2y-x^2+2xy-y^2`
`⇔-(x^2-2xy+y^2-2x+2y)`
`⇔-[(x-y)^2-2(x-y)]`
`⇔-(x-y)(x-y-2)`
13/
`x^3+2x^2y+xy^2-9x`
`⇔x(x^2+2xy+y^2-9)`
`⇔x[(x+y)^2-3^2]`
`⇔x(x+y-3)(x+y+3)`
Đáp án:
8) 3(x-y)+5x (x-y)
⇔ (3+5x)(x-y)
9) x(y-1)+y(1-y)
⇔ x(y-1)-y(y-1)
⇔ (x-y)(y-1)
10) x³-2x²+x
⇔ x(x²-2x+1)
⇔ x(x-1)²
11) 2x²+4x+2-2y²
⇔ 2(x²+2x+1-y²)
⇔ 2((x+1)²-y²)
⇔ 2(x+1-y).(x+1+y)
12) 2x-2y-x²+2xy-y²
13) x³+2x²2y+xy²-9x
⇔ x³+4x²y+xy²-9x
⇔ x(x²+4xy+y²-9)
Giải thích các bước giải: hì câu 12 ko bt lm