Bài 1:
a) (2x - y) + (2x - y) + (2x - y) + 3y
= 3(2x - y) + 3y
= 3(2x - y + 3y)
= 3(2x + 2y)
= 3.2(x + y)
= 6(x + y)

b) (x + 2y) + (x - 2y) + (8x - 3y)
= x + 2y + x - 2y + 8x - 3y
= 9x - 3y
= 3(3x - y)

c) (x + 2y) - 2(x - 2y) - (2x - 3y)
= x + 2y - 2x + 4y - 2x + 3y
= 9y - 3x
= 3(3y - x)

Bài 2:
M + 2(x² - 4y²) + Q = 6x² - 4xy + 5y² + P
M + 2x² - 8y²   -3x² + 7xy - 2y² = 6x² - 4xy + 5y² + 9x² - 6xy + 3y²
M + 2x² - 3x² - 6x² - 9x² - 8y² - 2y² - 5y² - 3y² + 7xy + 4xy + 6xy = 0
M - 16x² - 18y² + 17xy = 0
M = 16x² + 18y² - 17xy

a: \(P+\left(3x^2-4xy\right)=6y^2-9xy+x^2\)

=>\(P=x^2-9xy+6y^2-3x^2+4xy=-2x^2-5xy+6y^2\)

b: \(\left(4y^2-8xy\right)-P=5x^2-12xy+4y^2\)

=>\(P=4y^2-8xy-5x^2+12xy-4y^2=-5x^2+4xy\)

c: \(P-\left(x^2-2y^2+3z^2\right)+\left(3x^2-y^2+2z^2\right)=2x^2-3y^2-z^2\)

=>\(P=2x^2-3y^2-z^2+x^2-2y^2+3z^2-3x^2+y^2-2z^2\)

=>P=\(-4y^2\)

trả lời hộ với mai thi rồi

2x+3y+4xy=9

<=>4x+8xy+6y+3=21

<=>4x(2y+1)+3(2y+1)=21

<=>(2y+1)(4x+3)=21

đến đây lập bảng xét ước là ra

Answer:

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

\(=3x^2.2x^3+3x^2.(-x)+3x^2.5\)

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

\((4xy+3y-5x).x^2y\)

\(=4xy.x^2y+3y.x^2y-5x.x^2y\)

\(=4x^3+3x^2y^2-5x^3y\)