Không rút gọn được nữa

a) x²y³ - 1/2x⁴y⁸ = x²y³( 1 - 1/2x²y⁵ )

b) a²b⁴ + a³b - abc = ab( ab³ + a² - c )

c) 7x( y - 4 )² - ( y - 4 )³ = ( y - 4 )²( 7x - y + 4 )

d) -x²y²z - 6x³y - 8x⁴z² - x²y²z² = -x²( y²z + 6xy + 8x²z² + y²z² )

e) x³ - 4x² + x = x( x² - 4x + 1 )

Ta có : n² +  n + 1

= n² + 2n - n - 2 + 3

= n ( n + 2 ) - ( n + 2 ) + 3

= ( n - 1 ) ( n + 2 ) + 3

Vì ( n - 1 ) ( n + 2 )\(⋮\)n + 2 nên 3\(⋮\)n + 2

=> n + 2\(\in\){ \(\pm\)1 ; \(\pm\)3 }

=> n\(\in\){ - 5 ; - 3 ; - 1 ; 1 } ( tm n\(\in\)Z )

CHKB là hình bình hành suy ra CH // BK

\(=1.\left(2+1\right)\left(2^2+1\right)...\left(2^{256}+1\right)=\left(2-1\right)\left(2+1\right)...\left(2^{256}+1\right)\)

\(=\left(2^2-1\right)\left(2^2+1\right)\left(2^4+1\right)...\left(2^{256}+1\right)=\left(2^4-1\right)...\left(2^{256}+1\right)=....=2^{512}-1\)

A= (2-1) (2+1) (22+1) ........ + 1
= (22-1)(22+1) ......... (2256+1)
= (24-1) (24+ 1) ......... (2256+1)
................
= [(2256)2 –1] + 1
= 2512

đặt y = 1/x suy ra y <=1,

ta có P = 1 -2y+2016y^2 

Tự làm tiếp nhé

Make questions to the underlines works: 

We went to school by bus.

-->  Are they going to school by car?

Where does he live?

-> What!You don't know where I live!

Câu cuối chế

1.how did we go to school

cau a : (3x^2y-6xy+9x)(-4/3xy)

           =-4/3xy.3x^2y+4/3xy.6xy-4/3xy.9x

           =-4x+8-8y

cau b : (1/3x+2y)(1/9x^2-2/3xy+4y^2)

            =(1/3)^3-2/9x^2y+8y^3+4/3xy^2+2/9x^2y-4/3xy^2+8y^3

             =(1/3)^3 + (2y)^3x-2

cau c :  (x-2)(x^2-5x+1)+x(x^2+11)

            =x^3-5x^2+x-2x^2+10x-2+x^3+11x

            =2x^3-7x^2+22x-2

cau d := x^3 + 6xy^2 -27y^3

cau e := x^3 + 3x^2 -5x - 3x^2y - 9xy = 15y

cau f := x^2-2x+2x -4-2x-1

          = x(x-2)-5

cau e la + 15y ko phai =15y