Những câu hỏi liên quan
thanh dat nguyen
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Nguyễn Lê Phước Thịnh
20 tháng 10 2021 lúc 22:41

b: \(x^2-6x+xy-6y\)

\(=x\left(x-6\right)+y\left(x-6\right)\)

\(=\left(x-6\right)\left(x+y\right)\)

c: \(2x^2+2xy-x-y\)

\(=2x\left(x+y\right)-\left(x+y\right)\)

\(=\left(x+y\right)\left(2x-1\right)\)

e: \(x^3-3x^2+3x-1=\left(x-1\right)^3\)

Dương Thị Hoài Thư
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Uyên Hoàng Tố
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Yuki
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Trang Kieu
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Nguyễn Lê Phước Thịnh
22 tháng 10 2023 lúc 20:58

2:

a: \(x^2-12x+20\)

\(=x^2-2x-10x+20\)

=x(x-2)-10(x-2)

=(x-2)(x-10)

b: \(2x^2-x-15\)

=2x^2-6x+5x-15

=2x(x-3)+5(x-3)

=(x-3)(2x+5)

c: \(x^3-x^2+x-1\)

=x^2(x-1)+(x-1)

=(x-1)(x^2+1)

d: \(2x^3-5x-6\)

\(=2x^3-4x^2+4x^2-8x+3x-6\)

\(=2x^2\left(x-2\right)+4x\left(x-2\right)+3\left(x-2\right)\)

\(=\left(x-2\right)\left(2x^2+4x+3\right)\)

e: \(4y^4+1\)

\(=4y^4+4y^2+1-4y^2\)

\(=\left(2y^2+1\right)^2-\left(2y\right)^2\)

\(=\left(2y^2+1-2y\right)\left(2y^2+1+2y\right)\)

f; \(x^7+x^5+x^3\)

\(=x^3\left(x^4+x^2+1\right)\)

\(=x^3\left(x^4+2x^2+1-x^2\right)\)

\(=x^3\left[\left(x^2+1\right)^2-x^2\right]\)

\(=x^3\left(x^2-x+1\right)\left(x^2+x+1\right)\)

g: \(\left(x^2+x\right)^2-5\left(x^2+x\right)+6\)

\(=\left(x^2+x\right)^2-2\left(x^2+x\right)-3\left(x^2+x\right)+6\)

\(=\left(x^2+x\right)\left(x^2+x-2\right)-3\left(x^2+x-2\right)\)

\(=\left(x^2+x-2\right)\left(x^2+x-3\right)\)

\(=\left(x^2+x-3\right)\left(x+2\right)\left(x-1\right)\)

h: \(\left(x^2+2x\right)^2-2\left(x+1\right)^2-1\)

\(=\left(x^2+2x+1-1\right)^2-2\left(x+1\right)^2-1\)

\(=\left[\left(x+1\right)^2-1\right]^2-2\left(x+1\right)^2-1\)

\(=\left(x+1\right)^4-2\left(x+1\right)^2+1-2\left(x+1\right)^2-1\)

\(=\left(x+1\right)^4-4\left(x+1\right)^2\)

\(=\left(x+1\right)^2\left[\left(x+1\right)^2-4\right]\)

\(=\left(x+1\right)^2\left(x+1+2\right)\left(x+1-2\right)\)

\(=\left(x+1\right)^2\cdot\left(x+3\right)\left(x-1\right)\)

i: \(x^2+4xy+4y^2-4\left(x+2y\right)+3\)

\(=\left(x+2y\right)^2-4\left(x+2y\right)+3\)

\(=\left(x+2y\right)^2-\left(x+2y\right)-3\left(x+2y\right)+3\)

\(=\left(x+2y\right)\left(x+2y-1\right)-3\left(x+2y-1\right)\)

\(=\left(x+2y-1\right)\left(x+2y-3\right)\)

j: \(x\cdot\left(x+1\right)\left(x+2\right)\left(x+3\right)-3\)

\(=\left(x^2-3x\right)\left(x^2-3x+2\right)-3\)

\(=\left(x^2-3x\right)^2+2\left(x^2-3x\right)-3\)

\(=\left(x^2-3x+3\right)\left(x^2-3x-1\right)\)

LQM -LMHT
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Nguyen Le Ngoc Ha
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Trương Thành Đạt
8 tháng 6 2015 lúc 9:21

2x2-12x+18+2xy-6y=2(x2-6x+9+xy-3y)=2[(x2-6x+9)+(xy-3y)]=2[(x-3)2+y(x-3)]=2(x-3)(x+y-3)

Như Quỳnh
8 tháng 6 2015 lúc 9:22

2x2-12x+18+2xy-6y

=2(x2-6x+9+xy-3y)

=2 [(x2-6x+9)+(xy-3y)]

=2 (x-3)2+y(x-3)

=2(x-3)(x-3+y)

pham Duc Trieu
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Lê Thùy Dung
24 tháng 8 2016 lúc 12:01

4x^2 + 12x +9

= (2x)^2 + 2.2x.3 + 3^2

= ( 2x +3 ) ^2

Lê Thùy Dung
24 tháng 8 2016 lúc 11:58

x^2 - 2x - 15 

= x^2 - 5x + 3x - 15

= ( x^2 + 3x ) - (5x +15 )

= x ( x +3 ) - 5 ( x + 3 )

(x + 3 ) ( x - 5 )

Ngân Võ Thi Thu
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Kiệt Nguyễn
10 tháng 9 2019 lúc 14:32

1) 

a) \(2x^2-12x+18+2xy-6y\)

\(=2x^2-6x-6x+18+2xy-6y\)

\(=\left(2xy+2x^2-6x\right)-\left(6y+6x-18\right)\)

\(=x\left(2y+2x-6\right)-3\left(2y+2x-6\right)\)

\(=\left(x-3\right)\left(2y+2x-6\right)\)

\(=2\left(x-3\right)\left(y+x-3\right)\)

b) \(x^2+4x-4y^2+8y\)

\(=x^2+4x-4y^2+8y+2xy-2xy\)

\(=\left(-4y^2+2xy+8y\right)+\left(-2xy+x^2+4x\right)\)

\(=2y\left(-2y+x+4\right)+x\left(-2y+x+4\right)\)

\(=\left(2y+x\right)\left(-2y+x+4\right)\)

2)  \(5x^3-3x^2+10x-6=0\)

\(\Leftrightarrow x^2\left(5x-3\right)+2\left(5x-3\right)=0\Leftrightarrow\left(x^2+2\right)\left(5x-3\right)=0\)

Mà \(x^2+2>0\Rightarrow5x-3=0\Rightarrow x=\frac{3}{5}\)

\(x^2+y^2-2x+4y+5=0\)

\(\Leftrightarrow x^2+y^2-2x+4y+4+1=0\)

\(\Leftrightarrow\left(x^2-2x+1\right)+\left(y^2+4y+4\right)=0\)

\(\Leftrightarrow\left(x-1\right)^2+\left(y+2\right)^2=0\)

\(\Leftrightarrow\hept{\begin{cases}x-1=0\\y+2=0\end{cases}}\Leftrightarrow\hept{\begin{cases}x=1\\y=-2\end{cases}}\)

3)\(P\left(x\right)=x^2+y^2-2x+6y+12\)

\(P\left(x\right)=x^2+y^2-2x+6y+1+9+2\)

\(=\left(x^2-2x+1\right)+\left(y^2+6y+9\right)+2\)

\(=\left(x-1\right)^2+\left(y+3\right)^2+2\ge2\)

Vậy \(P\left(x\right)_{min}=2\Leftrightarrow\hept{\begin{cases}x-1=0\\y+3=0\end{cases}}\Leftrightarrow\hept{\begin{cases}x=1\\y=-3\end{cases}}\)

Bài làm

a) 2x2 - 12x + 18 + 2xy - 6y

= 2x2 - 6x - 6x + 18 + 2xy - 6y 

= ( 2xy + 2x2 - 6x ) - ( 6y + 6x - 18 )

= 2x( y + x - 3 ) - 6( y + x - 3 )

= ( 2x - 6 ) ( y + x - 3 )

# Học tốt #