Phân tích đa thức thành nhân tử:
\(a,x^4-2x^3+x^2-2x\)
\(b,x^4+x^3-8x-8\)
Bài 1: Tìm x , Biết
a) (x-4) x - (x-3)^2=0
b) 3x-6 = x^2-16
c) (2x-3)^2 - 49=0
d) 2x (x-5) - 7 (5-x)=0
Bài 2: Tìm m để đa thức
A(x)= 2x^3 + x^2 - 4x + m chia hết cho đa thức B(x)= 2x-1
Bài 3 : Phân tích đa thức thành nhân tử
a) x^2 - 8x
b) x^2 - xy - 6x + 6y
Bài 1:
b: \(3x-6=x^2-16\)
\(\Leftrightarrow x^2-3x-10=0\)
\(\Leftrightarrow\left(x-5\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-2\end{matrix}\right.\)
a: =64x^4+16x^2y^2+y^4-16x^2y^2
=(8x^2+y^2)^2-(4xy)^2
=(8x^2+y^2-4xy)(8x^2+y^2+4xy)
b: =x^8+2x^4+1-x^4
=(x^4+1)^2-x^4
=(x^4-x^2+1)(x^4+x^2+1)
=(x^4-x^2+1)(x^4+2x^2+1-x^2)
=(x^4-x^2+1)(x^2+1-x)(x^2+x+1)
c: =(x+1)(x^2-x+1)+2x(x+1)
=(x+1)(x^2-x+1+2x)
=(x+1)(x^2+x+1)
d: =(x^2-1)(x^2+1)-2x(x^2-1)
=(x^2-1)(x^2-2x+1)
=(x-1)^2*(x-1)(x+1)
=(x+1)(x-1)^3
Phân tích đa thức thành nhân tử
a) x^8+ x^7+ 1
b) 8x^4- 4x^3+ 2x^2+ 9x- 45
c) 16x^4- 16x^3+ 7x^2+ 9x- 9
d) 24x^4- 4x^3- 158x^2+ 25x+ 50
e) 2x^3- x^2- 15x- 22x+ 8
Phân tích đa thức sau thành nhân tử
a) 4x -4y +x^2 -2xy +y^2
b) x^4 -4x^3 -8x^2 +8x
c) x^3 +x^2 -4x -4
d) x^4 -x^2 +2x -1
a 4x -4y +(x-y)^2
=4(x-y)+(x-y).(x-y)
=(x-y).(4+x-y)
c x^2(x+1)-4(x+1)
(x+1).(x^2-4)
d x^4-(x^2-2x+1)
=x^4-(x-1)^2
=x^2(x-x+1)(x-x-1)
MIK KO BIT DUNG HAY KO CON B THI MIK KO BIET LAM
Câu b dễ thôi
\(x^4-4x^3-8x^2+8x\)
\(=x\left(x^3-4x^2-8x+8\right)\)
\(=x\left(x+2\right)\left(x^2-6x+4\right)\)
phân tích đa thức thành nhân tử
\(a) x^4-7x^2+6\)
\(b) x^4+2x^2-3\)
\(c) x^3-2x^2+5x-4\)
a) \(=\left(x^2-6\right)\left(x^2-1\right)=\left(x^2-6\right)\left(x-1\right)\left(x+1\right)\)
b) \(=\left(x^2-1\right)\left(x^2+3\right)=\left(x-1\right)\left(x+1\right)\left(x^2+3\right)\)
c) \(=x^2\left(x-1\right)-x\left(x-1\right)+4\left(x-1\right)=\left(x-1\right)\left(x^2-x+4\right)\)
phân tích đa thức sau thành nhân tử
6, x mũ 4 - 4x mũ 3 - 8x mũ 2 + 8x
8, x mũ 4 + 2x mũ 3 + x mũ 2 - y mũ 2
10, 4x mũ 2 ( x + y ) -x - y
6, x mũ 4 - 4x mũ 3 - 8x mũ 2 + 8x =x (x+2) (x^2-6x+4)
8, x mũ 4 + 2x mũ 3 + x mũ 2 - y mũ 2 = -(y-x^2-x) (y+x^2+x)
10, 4x mũ 2 ( x + y ) -x - y = (2x-1) (2x+1) (y+x)
Phân tích đa thức thành nhân tử
A= 6x^4-5x^3+4x^2+2x-1
B=4x^4+4x^3+5x^2+8x-6
C=x^4+x^3-5x^2+x-6
A = 6x4 - 5x3 + 4x2 + 2x - 1
= 6x4 + 3x3 - 8x3 - 4x2 + 8x2 + 4x - 2x - 1
= 3x3. ( 2x + 1 ) - 4x2 ( 2x + 1 ) + 4x ( 2x + 1 ) - ( 2x + 1 )
= ( 2x + 1 ) ( 3x3 - 4x2 + 4x - 1 )
= ( 2x + 1 ) ( 3x3 - x2 - 3x2 + x + 3x - 1 )
= ( 2x + 1 ) [ x2 ( 3x - 1 ) - x ( 3x - 1 ) + ( 3x - 1 ) ]
= ( 2x + 1 ) ( 3x - 1 ) ( x2 - x + 1 )
B = 4x4 + 4x3 + 5x2 + 8x - 6
= 4x4 - 2x3 + 6x3 - 3x2 + 8x2 - 4x + 12x - 6
= 2x3 ( 2x - 1 ) + 3x2 ( 2x - 1 ) + 4x ( 2x - 1 ) + 6 ( 2x - 1 )
= ( 2x - 1 ) ( 2x3 + 3x2 + 4x + 6 )
= ( 2x - 1 ) [ x2 ( 2x + 3 ) + 2 ( 2x + 3 ) ]
= ( 2x - 1 ) ( 2x + 3 ) ( x2 + 2 )
C = x4 + x3 - 5x2 + x - 6
= x4 - 2x3 + 3x3 - 6x2 + x2 - 2x + 3x - 6
= x3 ( x - 2 ) + 3x2 ( x - 2 ) + x ( x - 2 ) + 3 ( x - 2 )
= ( x - 2 ) ( x3 + 3x2 + x + 3 )
= ( x - 2 ) [ x2 ( x + 3 ) + ( x + 3 ) ]
= ( x - 2 ) ( x + 3 ) ( x2 + 1 )
Phân tích các đa thức sau thành nhân tử
b, x^3 - 2x^2 - 4xy^2 + x
c, (x+2) (x + 3) (x+4) (x+5) -8
\(b,x^3-2x^2-4xy^2+x\)
\(=x\left(x^2-2x-4y^2+1\right)\)
\(=x\left[\left(x^2-2x+1\right)-4y^2\right]\)
\(=x\left[\left(x-1\right)^2-\left(2y\right)^2\right]\)
\(=x\left(x-1-2y\right)\left(x-1+2y\right)\)
\(=x\left(x-2y-1\right)\left(x+2y-1\right)\)
\(---\)
\(c,\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-8\)
\(=\left[\left(x+2\right)\left(x+5\right)\right]\left[\left(x+3\right)\left(x+4\right)\right]-8\)
\(=\left(x^2+7x+10\right)\left(x^2+7x+12\right)-8\) (1)
Đặt \(y=x^2+7x+10\), thay vào (1) ta được:
\(y\left(y+2\right)-8\)
\(=y^2+2y+1-9\)
\(=\left(y+1\right)^2-3^2\)
\(=\left(y+1-3\right)\left(y+1+3\right)\)
\(=\left(y-2\right)\left(y+4\right)\)
\(=\left(x^2+7x+10-2\right)\left(x^2+7x+10+4\right)\)
\(=\left(x^2+7x+8\right)\left(x^2+7x+14\right)\)
#Ayumu
phân tích đa thức sau thành nhân tử
1, x mũ 2 - 4 - 3( x - 2 )
2, x mũ 2 - xy + 5y - 25
3, x mũ 3 + x mũ 2 - 2x - 8
4, x mũ 3 - 4x mũ 2 - 8x + 8
a, \(x^2-4-3\left(x-2\right)=\left(x-2\right)\left(x+2\right)-3\left(x-2\right)=\left(x-1\right)\left(x-2\right)\)
b, \(x^2-xy+5y-25=\left(x-5\right)\left(x+5\right)-y\left(x-5\right)=\left(x+5-y\right)\left(x-5\right)\)
c, \(x^3+x^2-2x-8=\left(x-2\right)\left(x^2+2x+4\right)+x\left(x-2\right)=\left(x-2\right)\left(x^2+3x+4\right)\)
d, \(x^3-4x^2-8x+8=\left(x+2\right)\left(x^2-2x+4\right)-4x\left(x+2\right)=\left(x^2-6x+4\right)\left(x+2\right)\)
Trả lời:
1, x2 - 4 - 3 ( x - 2 )
= ( x2 - 4 ) - 3 ( x - 2 )
= ( x - 2 ) ( x + 2 ) - 3 ( x - 2 )
= ( x - 2 ) ( x + 2 - 3 )
= ( x - 2 ) ( x - 1 )
2, x2 - xy + 5y - 25
= ( x2 - 25 ) - ( xy - 5y )
= ( x - 5 ) ( x + 5 ) - y ( x - 5 )
= ( x - 5 ) ( x + 5 - y )
3, x3 + x2 - 2x - 8
= ( x3 - 8 ) + ( x2 - 2x )
= ( x - 2 ) ( x2 + 2x + 4 ) + x ( x - 2 )
= ( x - 2 ) ( x2 + 2x + 4 + x )
= ( x - 2 ) ( x2 + 3x + 4 )
4, x3 - 4x2 - 8x + 8
= ( x3 + 8 ) - ( 4x2 + 8x )
= ( x + 2 ) ( x2 - 2x + 4 ) - 4x ( x + 2 )
= ( x + 2 ) ( x2 - 2x + 4 - 4x )
= ( x + 2 ) ( x2 - 6x + 4 )