a) \(\left(3x+y-z\right)-\left(4x-2y+6z\right)\)

\(=3x+y-z-4x+2y-6z\)

\(=-x+3y-7z\)

b) \(\left(x^3+6x^2+5y^3\right)-\left(2x^3-5x+7y^3\right)\)

\(=x^3+6x^2+5y^3-2x^3+5x-7y^3\)

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

c) \(\left(5,7x^{2y}-3,1xy+8y^3\right)-\left(6,9xy-2,3x^{2y}-8y^3\right)\)

\(=5,7x^{2y}-3,1xy+8y^3-6,9xy+2,3x^{2y}+8y^3\)

\(=8x^{2y}-10xy+16y^3\)

a) (1,2x - 3,5y + 2) - (0,2x - 2,5y + 3)

= 1,2x - 3,5y + 2 - 0,2x + 2,5y - 3

= x - y - 1

b) (5,7x²y - 3,1xy + 8y³) - (6,9xy - 2,3x²y + 8y³).

= 5,7x²y - 3,1xy + 8y³ - 6,9xy + 2,3x²y - 8y³

= 3,4 x²y - 10xy

giúp tớ với

\(\left(\dfrac{x}{x+2y}-\dfrac{x+2y}{2y}\right)\left(\dfrac{x}{x-2y}-1+\dfrac{8y^3}{8y^3-x^3}\right)=\dfrac{2xy-\left(x+2y\right)^2}{2y\left(x+2y\right)}\left(\dfrac{2y}{x-2y}+\dfrac{8y^3}{\left(2y-x\right)\left(4y^2+2yx+x^2\right)}\right)=\dfrac{-\left(x^2+2xy+4y^2\right)}{2y\left(x+2y\right)}\cdot\dfrac{2y\left(4y^2+2yx+x^2\right)-8y^3}{\left(x-2y\right)\left(x^2+2xy+4y^2\right)}=\dfrac{-\left(x^2+2xy+4y^2\right)2y\left(4y^2+2xy+x^2-4y^2\right)}{2y\left(x+2y\right)\left(x-2y\right)\left(x^2+2x+4y^2\right)}=\dfrac{-\left(x^2+2xy\right)}{\left(x+2y\right)\left(x-2y\right)}=\dfrac{x}{2y-x}\)

a: \(=3x+y-z-4x+2y-6z=-x+3y-7z\)

b: \(=x^3+6x^2+5y^3-2x^3+5x-7y^3=-x^3+6x^2+5x-2y^3\)

c: \(=5.7x^2y-3.1xy+8y^3-6.9xy+2.3x^2y+8y^3\)

\(=8x^2y-10xy+16y^3\)

Ta có : \(P=-9x^2y+8y^3-3x;Q=-8y^3+8x\)

\(\Rightarrow P+Q=-9x^2y+8y^3-3x-8y^3+8x\)

\(=-9x^2y+5x\)

2(2y + 1)(8y - 3) + (3 - 4y)(8y - 7) = 6y + 73

32y² - 12y + 16y - 6 + 24y - 21 - 32y² + 28y = 6y + 73

56y - 27 = 6y + 73

56y - 6y = 73 + 27

50y = 100

y = 100 : 50

y = 2

2(2y + 1)(8y - 3) + (3 - 4y)(8y - 7) = 6y + 73

32y2 - 12y + 16y - 6 + 24y - 21 - 32y2 + 28y = 6y + 73

56y - 27 = 6y + 73

56y - 6y = 73 + 27

50y = 100

y = 100 : 50

y = 2

tick và theo dõi giúp mình nha