Phân tích các đa thức sau thành nhân tử:
a) x3−2x2+xx3−2x2+x ;
b) 2x2+4x+2−2y22x2+4x+2−2y2 ;
c) 2xy−x2−y2+16
Phân tích đa thức thành nhân tử:
a) x3 +8y3
b) x3 - 2x2 - x + 2
c) 25 - 16x2
\(a,x^3+8y^3=\left(x+2y\right)\left(x^2-2xy+4y^2\right)\\ v,x^3-2x^2-x+2=\left(x^3-2x^2\right)-\left(x-2\right)=x^2\left(x-2\right)-\left(x-2\right)=\left(x-2\right)\left(x^2-1\right)=\left(x-1\right)\left(x+1\right)\left(x-2\right)\\ c,25-16x^2=\left(5-4x\right)\left(5+4x\right)\)
\(a,=\left(x+2y\right)\left(x^2-2xy+4y^2\right)\\ b,=x^2\left(x-2\right)-\left(x-2\right)\\ =\left(x-2\right)\left(x^2-1\right)=\left(x-1\right)\left(x-2\right)\left(x+2\right)\\ c,=\left(5-4x\right)\left(5+4x\right)\)
Phân tích đa thức thành nhân tử:
a) x3 - 2x2 - 2x - 4
b) xy + 1 - x - y
c) x2 - 4xy + 4y2 - 4y
d) 16 - x2 + 2xy - y2
\(a.x^3-2x^2-2x-4\\ =\left(x^3-2x^2\right)-\left(2x-4\right)\\ =x^2\left(x-2\right)-2\left(x-2\right)\\ =\left(x^2-2\right)\left(x-2\right)\)
\(b.xy+1-x-y\\ =\left(xy-x\right)+\left(-y+1\right)\\ =x\left(y-1\right)-\left(y-1\right)\\ =\left(x-1\right)\left(y-1\right)\)
\(c.x^2-4xy+4y^2-4y\\ =\left(x-2y\right)^2-4y\\ =\left(x-2y\right)^2-\left(2y\right)^2\\ =\left(x-2y+2y\right)\left(x-2y-2y\right)\\ =x\left(x-4y\right)\)
\(d.16-x^2+2xy-y^2\\ =4^2-\left(x-y\right)^2\\ =\left(4-x+y\right)\left(4-x-y\right)\)
b: =xy-x-y+1
=x(y-1)-(y-1)
=(x-1)(y-1)
c: =(x-2y)^2-4y
\(=\left(x-2y-2\sqrt{y}\right)\left(x-2y+2\sqrt{y}\right)\)
d: =16-(x^2-2xy+y^2)
=16-(x-y)^2
=(4-x+y)(4+x-y)
Bài 10:: Phân tích các đa thức sau thành nhân tử:
a) x3 - 2x2 + x b) x2 – 2x – 15 c) 5x2y3 – 25x3y4 + 10x3y3 d) 12x2y – 18xy2 – 30y2
| e) 5(x-y) – y.( x – y) g)36 – 12x + x2 h) 4x2 + 12x + 9 i) 11x + 11y – x2 – xy |
Phân tích các đa thức sau thành nhân tử:
a,x3+4x-5
b,x3-3x2+4
c,x3+2x2+3x+2
d,x2+2xy+y2+2x-2y-3
e,(x2+3x)2-2(x2+3x)-8
f,(x2+4x+10)2-7(x2+4x+11)+7
a) x3+4x-5 = x3-x2+x2+4x-5=(x3-x2)+(x2-x)+(5x-5)=x2(x-1)+x(x-1)+5(x-1)=(x2+x+5)(x-1)
b) x3-3x2+4=x3-2x2-x2+4=(x3-2x2)-(x2-4)=x2(x-2)-(x-2)(x+2)=(x2-x+2)(x-2)
c) x3+2x2+3x+2=x3+x2+x2+x+2x+2=(x3+x2)+(x2+x)+(2x+2)=x2(x+1)+x(x+1)+2(x+1)=(x2+x+2)(x+1)
d) bạn xem lại đề đúng ko
e) (x2+3x)2-2(x2+3x)-8=x4+6x3+9x2-2x2-6x-8=x4+6x3+7x2-6x-8=x4-x3+7x3-7x2+14x2-14x+8x-8=(x4-x3)+(7x3-7x2)+(14x2-14x)+(8x-8)=x3(x-1)+7x2(x-1)+14x(x-1)+8(x-1)=(x3+7x2+14x+8)(x-1)=(x3+x2+6x2+6x+8x+8)(x-1)=\(\left[\left(x^3+x^2\right)+\left(6x^2+6x\right)+\left(8x+8\right)\right]\left(x-1\right)\)\(=\left[x^2\left(x+1\right)+6x\left(x+1\right)+8\left(x+1\right)\right]\left(x-1\right)\)\(=\left(x^2+6x+8\right)\left(x+1\right)\left(x-1\right)\)\(=\left(x^2+2x+4x+8\right)\left(x+1\right)\left(x-1\right)\)\(=\left[\left(x^2+2x\right)+\left(4x+8\right)\right]\left(x+1\right)\left(x-1\right)\)\(=\left[x\left(x+2\right)+4\left(x+2\right)\right]\left(x+1\right)\left(x-1\right)\)=\(\left(x-1\right)\left(x+1\right)\left(x+2\right)\left(x+4\right)\)
f) (x2+4x+10)2-7(x2+4x+11)+7=(x2+4x+10)2-\(\left[7\left(x^2+4x+11\right)-7\right]\)\(=\left(x^2+4x+10\right)^2-7\left(x^2+4x+10\right)\)\(=\left(x^2+4x+10\right)\left(x^2+4x+3\right)\)
a) Ta có: \(x^3+4x-5\)
\(=x^3-x+5x-5\)
\(=x\left(x-1\right)\left(x+1\right)+5\left(x-1\right)\)
\(=\left(x-1\right)\left(x^2+x+5\right)\)
b) Ta có: \(x^3-3x^2+4\)
\(=x^3+x^2-4x^2+4\)
\(=x^2\left(x+1\right)-4\left(x-1\right)\left(x+1\right)\)
\(=\left(x+1\right)\left(x^2-4x+4\right)\)
\(=\left(x+1\right)\cdot\left(x-2\right)^2\)
c) Ta có: \(x^3+2x^2+3x+2\)
\(=x^3+x^2+x^2+x+2x+2\)
\(=x^2\left(x+1\right)+x\left(x+1\right)+2\left(x+1\right)\)
\(=\left(x+1\right)\left(x^2+x+2\right)\)
d) Ta có: \(x^2+2xy+y^2+2x+2y-3\)
\(=\left(x+y\right)^2+2\left(x+y\right)-3\)
\(=\left(x+y\right)^2+3\left(x+y\right)-\left(x+y\right)-3\)
\(=\left(x+y\right)\left(x+y+3\right)-\left(x+y+3\right)\)
\(=\left(x+y+3\right)\left(x+y-1\right)\)
e) Ta có: \(\left(x^2+3x\right)^2-2\left(x^2+3x\right)-8\)
\(=\left(x^2+3x\right)^2-4\left(x^2+3x\right)+2\left(x^2+3x\right)-8\)
\(=\left(x^2+3x\right)\left(x^2+3x-4\right)+2\left(x^2+3x-4\right)\)
\(=\left(x^2+3x-4\right)\left(x^2+3x+2\right)\)
\(=\left(x+4\right)\left(x-1\right)\left(x+1\right)\left(x+2\right)\)
f) Ta có: \(\left(x^2+4x+10\right)^2-7\left(x^2+4x+11\right)+7\)
\(=\left(x^2+4x+10\right)^2-7\left(x^2+4x+10\right)-7+7\)
\(=\left(x^2+4x+10\right)\left(x^2+4x+10-7\right)\)
\(=\left(x^2+4x+3\right)\left(x^2+4x+10\right)\)
\(=\left(x+1\right)\left(x+3\right)\left(x^2+4x+10\right)\)
Câu 2: Phân tích các đa thức sau thành nhân tử:
a) 3x. (x – 2 ) – 4x + 8 b) – 6xy2 + 6x3 + 12x2 + 6x
c) 2x2 + 4x – 30
phân tích đa thức thành nhân tử
x2-4y2+x+1
tìm x
x3-2x2-10x=0
\(\left(x-2y\right)\left(x+2y\right)+\left(x+1\right)\)
Phân tích đa thức sau thành nhân tử:
a) x2 - 2x - 4y2 - 4y
b) 2x2 + 3x - 5
a: \(=\left(x-2y\right)\left(x+2y\right)-2\left(x+2y\right)=\left(x+2y\right)\left(x-2y-2\right)\)
a)x2-2x-4y2-4y
=x2-2x-4y2-4y+1-1
=(x2-2x+1)-(4y2+4y+1)
=(x-1)2-(2y+1)2
=(x-2y-2)(x+2y)
b)2x2+3x-5
=2x2-2x+5x-5
=2x(x-1)+5(x-1)
=(x-1)(2x+5)
Phân tích đa thức sau thành nhân tử: x3 – 2x2 + x.
x3 – 2x2 + x
= x.x2 – x.2x + x (Xuất hiện nhân tử chung là x)
= x(x2 – 2x + 1) (Xuất hiện hằng đẳng thức (2))
= x(x – 1)2
Phân tích đa thức sau thành nhân tử : x3+ 2x2 +x
\(x^3+2x^2+x\)
\(=x\left(x^2+2x+1\right)\)
\(=x\left(x+1\right)^2\)
\(x\left(x^2+2x+1\right)=x\left(x+1\right)^2\)