\(\left(2a-b-2\right)\left(a+3b+1\right)\)

Bạn ơi làm thế nào để ra kết quả đấy thế?

1 ) 3yx - 6xy² 

= 3xy ( 1 - 2y )

2 ) 5ab² - 20a³b²

= 5ab² ( 1 - 4a² )

= 5ab² ( 1 - 2a ) ( 1 + 2a )

3 ) 3x - 3b - y ( b - x )

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

= ( x - b ) ( 3 + y ) 

1)3xy-6xy²=3xy(1-2y)

2)5ab²-20a³b²=5ab²(1-4a²)=5ab²[1²-(2a)²]=5ab²(1+2a)(1-2a)

3)3x-3b-y(b-x)=3x-3b-by+xy=(3x+xy)-(3b+by)=3x(1+y)-3b(1+y)=3(1+y)(x-b)

\(3xy-6\left(xy\right)^2=3xy.\left(1-2xy\right)\)

\(5\left(ab\right)^2-20a^3b^2=5a^2b^2\left(1-4a\right)\)

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

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Vào đây xem nha 

https://h7.net/hoi-dap/toan-8/phan-h-da-thuc-4x-2-2x-3y-9y-2-thanh-nhan-tu-faq289539.html

hoctot

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

                =x^3.(x^2+x+1) - x(x^2+x+1)+(x^2+x+1)

                =(x^2+x+1)(x^3-x+1)

\(2a^2+5ab-2b^2\)

\(=2a^2+ab+4ab-2b^2\)

\(=a\left(2a+b\right)+2b\left(2a+b\right)\)

\(=\left(2a+b\right)\left(a+2b\right)\)

vì sao lại x^5+x^4+1=(x^5+x^4+1)-(x^3+x^2+x)+(x^2+x+1)