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AH
Akai Haruma
Giáo viên
9 tháng 8 2021

Bạn cần làm gì với những đa thức này?

9 tháng 8 2021

a) \(25x^2y-10xy+30xy^2=xy\left(25x+30y-10\right)\) 

b) \(16x^2-20x=4x\left(4x-5\right)\)

c) \(18x^3+12x^2-30x=x\left(18x^2+12x-30\right)=x\left(x-1\right)\left(18x+9\right)=96x\left(x-1\right)\left(x+\dfrac{5}{3}\right)\)

d) \(14x\left(x+y\right)-4y\left(x+y\right)=\left(14x-4y\right)\left(x+y\right)\)

e) \(9x^3y^2+12xy^2+15x^2y^2=3xy^2\left(3x^2+5x+4\right)\)

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

g) \(5x\left(x+4\right)-2y\left(4+x\right)=\left(x+4\right)\left(5x-2y\right)\)

Bài 1:

a)\(5x^2y^3-25x^3y^4+10x^3y^3=5x^2y^3\left(1-5xy+2x\right)\)

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

c)Đề sai hoàn toàn

d) \(2x^2+4xy+2y^2-8z^2=2\left(x^2+2xy+y^2-4z^2\right)=2\left[\left(x+y\right)^2-\left(2z\right)^2\right]=2\left(x+y-2z\right)\left(x+y+2z\right)\)e) \(3x-3a+yx-ya=3\left(x-a\right)+y\left(x-a\right)=\left(x-a\right)\left(3+y\right)\)

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

g)\(2x^2-5x+2=2x^2-x-4x+2=x\left(2x-1\right)-2\left(2x-1\right)=\left(2x-1\right)\left(x-2\right)\)

i)\(14x\left(x-y\right)-21y\left(y-x\right)+28z\left(x-y\right)=14x\left(x-y\right)+21y\left(x-y\right)+28z\left(x-y\right)=7\left(x-y\right)\left(2x+3y+4z\right)\)

17 tháng 6 2017

b1:

câu a,f áp dụng a2-b2=(a-b)(a+b)

câu b,c áp dụng a3-b3=(a-b)(a2+ab+b2)

câu d: \(x^2+2xy+x+2y=x\left(x+2y\right)+\left(x+2y\right)=\left(x+1\right)\left(x+2y\right)\)

câu e: \(7x^2-7xy-5x+5y=7x\left(x-y\right)-5\left(x-y\right)=\left(7x-5\right)\left(x-y\right)\)

câu g xem lại đề

17 tháng 6 2017

b2:

\(f\left(x;y\right)=x^2+y^2-6x+5y+9=\left(x^2-6x+9\right)+\left(y^2+5y+\frac{25}{4}\right)-\frac{25}{4}\)

\(=\left(x-3\right)^2+\left(y+\frac{5}{2}\right)^2-\frac{25}{4}\ge-\frac{25}{4}\)

Dấu "=" xảy ra khi x=3 và y=-5/2

câu c làm tương tự

13 tháng 10 2018

1.a)\(20x-5y=5\left(4x-y\right)\)

b)\(5x\left(x-1\right)-3x\left(x-1\right)=\left(5x-3x\right)\left(x-1\right)=2x\left(x-1\right)\)

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

d)\(6x^3-9x^2=3x^2\left(2x-3\right)\)

e)\(4x^2y-8xy^2+10x^2y^2=2xy\left(2x-8y+10xy\right)\)

g)\(20x^2y-12x^3=4x^2\left(5y-3x\right)\)

h)\(8x^4+12x^2y-16x^3y^4=4x^2\left(2x^2+12y-16xy^4\right)\)

13 tháng 10 2018

2.a)\(3x\left(x+1\right)-5y\left(x+1\right)=\left(3x-5y\right)\left(x+1\right)\)

b)\(3x\left(x-6\right)-2\left(x-6\right)=\left(3x-2\right)\left(x-6\right)\)

c)\(4y\left(x-1\right)-\left(1-x\right)=4y\left(x-1\right)+\left(x-1\right)=\left(4y+1\right)\left(x-1\right)\)

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

e)\(7x\left(x-y\right)-\left(y-x\right)=7x\left(x-y\right)+\left(x-y\right)=\left(7x+1\right)\left(x-y\right)\)

h)\(3x^3\left(2y-3z\right)-15x\left(2y-3z\right)^2=3x\left(2y-3z\right)\left[x^2-5\left(2y-3z\right)\right]\)

k)Sai đề: \(3x\left(z+2\right)+5\left(-z-2\right)=3x\left(z+2\right)-5\left(z+2\right)=\left(3x-5\right)\left(z+2\right)\)

l)\(18x^2\left(3+x\right)+3\left(x+3\right)=3\left(x+3\right)\left(6x^2+1\right)\)

m)\(14x^2y-21xy^2+28x^2y^2=7xy\left(2x-3y+4xy\right)\)

n)\(10x\left(x-y\right)-8y\left(y-x\right)=10x\left(x-y\right)+8y\left(x-y\right)=2\left(5x+4y\right)\left(x-y\right)\)

12 tháng 10 2019

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

b) \(x^2+16x+64=\left(x+8\right)^2\)

c) \(x^3-8y^3=x^3-\left(2y\right)^3\)

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

d) \(9x^2-12xy+4y^2=\left(3x-2y\right)^2\)

b: \(=\left(x+3+y\right)\left(x+3-y\right)\)

c: \(=x\left(9x^2-6xy+y^2\right)=x\left(3x-y\right)^2\)

d: \(=\left(xy+6\right)\left(x^2y^2-6xy+36\right)\)

e: \(=\left(x+y-3\right)\left(x^2+2xy+y^2+3x+3y+9\right)\)

30 tháng 7 2018

từ từ ít ít từng câu thôi bạn ơi

16 tháng 7 2018

1)  \(x^6-x^4-9x^3+9x^2\)

\(=x^2\left(x^4-x^2-9x+9\right)\)

\(=x^2\left[x^2\left(x^2-1\right)-9\left(x-1\right)\right]\)

\(=x^2\left(x-1\right)\left[x^2\left(x+1\right)-9\right]\)

\(=x^2\left(x-1\right)\left(x^3+x^2-9\right)\)

2)   \(x^4-4x^3+8x^2-16x+16\)

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

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

18 tháng 7 2018

3) \(x^4-25x^2+20x-4=x^4+5x^3-2x^2-5x^3-25x^2+10x+2x^2+10x-4\)

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

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

4) \(5x\left(x-2y\right)+2\left(2y-x\right)^2\)\(=5x\left(x-2y\right)+2\left(x-2y\right)^2=\left(x-2y\right)\left(5x+2x-4y\right)=\left(x-2y\right)\left(7x-4y\right)\)

5) \(x^2\left(x^2-6\right)-x^2+9=x^4-7x^2+9\)

\(=x^4+x^3-3x^2-x^3-x^2+3x-3x^2-3x+9\)

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

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

6) \(7x\left(y-4\right)^2-\left(4-y\right)^3=7x\left(y-4\right)^2+\left(y-4\right)^3=\left(y-4\right)^2\left(7x+y-4\right)\)

7) \(x^3+2x^2-6x-27=x^3-3x^2+5x^2-15x+9x-27\)

\(=x^2\left(x-3\right)+5x\left(x-3\right)+9\left(x-3\right)=\left(x-3\right)\left(x^2+5x+9\right)\)

12 tháng 7 2019

a,\(xy+3x-7y-21\)

\(=x\left(y+3\right)-7\left(y+3\right)\)

\(=\left(y+3\right)\left(x-7\right)\)

12 tháng 7 2019

\(b,2xy-15-6x+5y\)

\(=\left(2xy-6x\right)+\left(-15+5y\right)\)

\(=2x\left(y-3\right)-5\left(3-y\right)\)

\(=2x\left(y-3\right)+5\left(y-3\right)\)

\(=\left(y-3\right)\left(2x+5\right)\)

24 tháng 12 2017

a) (x3 + 8y3) : (2y + x)

= (x + 2y)(x2 - 2xy + 4y2) : (2y + x)

= x2 - 2xy + 4y2

b) (x3 + 3x2y + 3xy2 + y3) : (2x + 2y)

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

= \(\dfrac{\left(x+y\right)^2}{2}\)

c) (6x5y2 - 9x4y3 + 15x3y4) : 3x3y2

= 3x3y2(2x2 - 3xy + 5y2) : 3x3y2

= 2x2 - 3xy + 5y2