a)  \(x^2y-xy^2-3x+3y\)

\(=xy\left(x-y\right)-3\left(x-y\right)\)

\(=\left(x-y\right)\left(xy-3\right)\)

b)  \(5x^4-20=5\left(x^4-4\right)\)

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

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

c)  \(x^2-9x+20\)

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

\(=x\left(x-4\right)-5\left(x-4\right)\)

\(=\left(x-4\right)\left(x-5\right)\)

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

\(5x^4-20=5.\left[\left(x^2\right)^2-2^2\right]=5.\left(x^2-2\right).\left(x^2+2\right)\)

\(x^2-9x+20=\left(x^2-2.4,5x+4,5^2\right)-0,25=\left(x-20,25\right)^2-0,5^2\)\(=\left(x-20,25+0,5\right).\left(x-20,25-0,5\right)=\left(x-19,75\right).\left(x-20,75\right)\)

Tham khảo nhé~

đầu bài đâu

cái đề kiểu gì vậy :/

\(-2x^4-7x^3-x^2+7x+3\)

\(=-2x^3\left(x+1\right)-5x^2\left(x+1\right)+4x\left(x+1\right)+3\left(x+1\right)\)

\(=-\left(x+1\right)\left(2x^3+5x^2-4x-3\right)\)

\(=-\left(x+1\right)\left[2x^2\left(x-1\right)+7x\left(x-1\right)+3\left(x-1\right)\right]\)

\(=-\left(x+1\right)\left(x-1\right)\left(2x^2+7x+3\right)\)

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

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

\(A=x^3+8-\left[x^3+1+3x\left(x+1\right)\right]+3\left(x^2-1\right)\)

\(A=x^3+8-x^3-1-3x\left(x+1\right)+3x^2-3\)

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

\(A=4-3x\)

b/ Để \(\left|A\right|=A\)

=> \(A\ge0\)

<=> \(4-3x\ge0\)

<=> \(4\ge3x\)

<=> \(x\ge\frac{3}{4}\)

Vậy khi \(x\ge\frac{3}{4}\)thì \(\left|A\right|=A\).

Chữ U nha.

10h30 phút = 10,5 giờ

Vận tốc giảm là:

40 - 30 = 10 (km/giờ)

Quãng đường AB dài là:

10,5 x 10 = 105 (km)

           Đáp số: 105 km

Đổi : 10 giờ 30 phút = 10 , 5 giờ

Vận tốc khi giảm là :

40 - 30 = 10 ( km / giờ )

Quãng đường AB dài là : 

10 ,5 x 10 = 105 ( km )

Đáp số : 105 km .

\(a,27-x^3\)

\(=3^3-x^3\)

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

Các câu còn lại lm tương tự nhé.

hok tốt!

a)  \(27-x^3=\left(3-x\right)\left(9+3x+x^2\right)\)

b)  \(8x^3+0,001=\left(2x+0,1\right)\left(4x^2-0,2x+0,01\right)\)

c)  \(\frac{x^3}{125}-\frac{y^3}{27}=\left(\frac{x}{5}-\frac{y}{3}\right)\left(\frac{x^2}{25}+\frac{xy}{15}+\frac{y^2}{9}\right)\)

p/s: chúc bạn học tốt

a)  \(27x^3-8=\left(3x-2\right)\left(9x^2+6x+4\right)\)

b)  \(8x^3+12x^2+6x+1=\left(2x+1\right)^3\)

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

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

do hơi bận nên mk ghi đáp án nha, ko hiểu đâu ib mk 

a)  \(3xy^2-2xy+12x=x\left(3y^2-2y+12\right)\)

b)  \(x^3-10x^2+25x-16xy^2=x\left(x-4y-5\right)\left(x+4y-5\right)\)

c)  \(5y^3-10xy^2+5x^2y-20y=5y\left(y-x-2\right)\left(y-x+2\right)\)

d)  \(x^2+2xy+y^2-xz-yz=\left(x+y\right)\left(x+y-z\right)\) 

e)  \(9x^2+y^2+6xy=\left(3x+y\right)^2\)

f)  \(8-12x+6x^2-x^3=\left(2-x\right)^3\)

g)  \(125x^3-75x^2+15x-1=\left(5x-1\right)^3\)

h)  \(x^2-xz-9y^2+3yz=\left(x-3y\right)\left(x+3y-z\right)\)

= x³ + 9x² + 81x + 27  - x³ - 64

= 9x² + 81x - 34