a, Ta có  \(M+N=7xyz-2x^2-2+y^2\)

 \(M-N=3xyz-8x^2+16xy+12-y^2\)

\(N-M=8x^2-3xyz-16xy-12+y^2\)

* Đa thức thu gọn là đa thức không còn hai hạng tử nào đồng dạng

A = (xy⁷- xy⁷) + (x³y⁵-x³y⁵)+x⁸+10

A = x⁸+10

* M + N

= (5xyz -5x² + 8xy + 5)+(5x²+2xyz-8xy-7+y²)

= 5xyz - 5x² +8xy +5+5x² +2 xyz - 8xy -7 + y²

= ( 5xyz + 2xyz ) + ( -5x² +5x²) + ( 8xy - 8xy ) + ( 5-7) +y²

= 7xyz - 2 + y²

* M - N

= ( 5xyz - 5x² +8xy +5) - ( 5x² + 2xyz - 8xy -7 +y²)

= 5xyz - 5x² + 8xy + 5 - 5x² - 2xyz + 8xy + 7 - y²

= ( 5xyz - 2xyz) + ( -5x² - 5x²) + ( 8xy + 8xy) + ( 5+7) -y²

= 3xyz - 10x² +16xy +12 -y²

\(M=xy^3+5xyz-4x^2+6-x^3y+2xyz-xy^3+x^2-5\)

     \(=7xyz-3x^2-x^3y+1\)

\(a,5xyz-12x^2yz^2-17xy^3-21x^2yz^2-6xyz+M=0\)

\(\Rightarrow-xyz-33x^2yz^2-17xy^3+M=0\)

\(\Rightarrow M=xyz+33x^2yz^2+17xy^3\)

Vậy...

b, \(M-\left(6x^4y^3-7xyz^3+9xyz\right)=4x^4y^3-3xyz^3-5xyz\)

\(\Rightarrow M=4x^4y^3-3xyz^3-5xyz+6x^4y^3-7xyz^3+9xyz\)

\(\Rightarrow M=10x^4y^3-10xyz^3+4xyz\)

Vậy...

a) Ta có:

\(M=-xyz+12x^2yz^2+17xy^3+21x^2yz^2+6xyz\)

\(=xyz+33x^2yz^2+17xy^3\)

b) \(M=4x^4y^3-3xyz^3-5xyz+\left(6x^4y^3-7xyz^3+9xyz\right)\)

\(=4x^4y^3+6x^4y^3-3xyz^3-7xyz^3-5xyz+9xyz\)

\(=10x^4y^3-10xyz^3+4xyz\)

a, \(5xyz-12x^2yz^2-17xy^3-21x^2yz^2-6xyz+M=0\)

\(\Rightarrow M=-5xyz+12x^2yz^2+17xy^3+21x^2yz^2+6xyz\)

\(\Rightarrow M=\left(-5xyz+6xyz\right)+\left(12x^2yz^2+21x^2yz^2\right)+17xy^3\)

\(\Rightarrow M=xyz+33x^2yz^2+17xy^3\)

b, \(M-\left(6x^4y^3-7xyz^3+9xyz\right)=4x^4y^3-3xyz^3-5xyz\)

\(\Rightarrow M=4x^4y^3-3xyz^3-5xyz+\left(6x^4y^3-7xyz^3+9xyz\right)\)

\(\Rightarrow M=4x^4y^3-3xyz^3-5xyz+6x^4y^3-7xyz^3+9xyz\)

\(\Rightarrow M=\left(4x^4y^3+6x^4y^3\right)+\left(-3xyz^3-7xyz^3\right)+\left(-5xyz+9xyz\right)\)

\(\Rightarrow M=10x^4y^3-10xyz^3+4xyz\)

Chúc bạn học tốt!!!

`a)`

`A-B=(6x^2-7xy-4y^2)-(-2x^2+7xy+5y^2)`

      `=6x^2-7xy-4y^2+2x^2-7xy-5y^2`

      `=(6x^2+2x^2)-(7xy+7xy)-(4y^2+5y^2)`

      `=8x^2-14xy-9y^2`

___________________________________________

`b)`

`Q-(3x^4-2xyz)=xy+3x^4-5xyz-713`

`Q=(xy+3x^4-5xyz-713)+(3x^4-2xyz)`

`Q=xy+3x^4-5xyz-713+3x^4-2xyz`

`Q=xy+6x^4-7xyz-713`

a) A= 12-7xy-4y^2

    B=-4+7xy+5y^2

A-B= 16-14xy-9y^2

b) Q(x)= xy+12-5xyz-713+12-2xyz

           = xy+(12+12-713)+(-5xyz-2xyz)

           = xy-689-7xyz

Chúc bạn học tốt !

a) tự tính nhé dễ mà

b) M + N = 5xyz - 5x² + 8xy + 5 + 3x² + 2xyz - 8xy - 7 + y²

              = 5xyz + 2xyz + (-5x² + 3x²) + 8xy - 8xy  + y² + 5 - 7

              = 7xyz - 2x² + y² - 2

M - N và N - M làm tương tự nhé

M+N=(5xyz-5x\(^2\)+8xy+5) + (3x\(^2\)+2xyz-8xy-7+y\(^2\))

=(5xyz+2xyz)-(5x\(^2\)+3x\(^2\))+(8xy-8xy)+(5-7)

=7xyz-2x\(^2\)-2

Mk lm cho bn tương tự bn lm như z ý k khó đâu

Chúc bạn học tốt!

M+N=(5xyz -5x² +8xy+5)+(3x² +2xyz -8xy-7+y²)

=5xyz -5x² +8xy+5+3x² +2xyz -8xy-7+y²

=(5xyz-2xyz)+(5x²+3x²)+(8xy-8xy)+(5-7)+y²

=3xyz+8x²+0+(-2)+y²

=3xyz+8x²+(-2)

M-N=(5xyz -5x² +8xy+5)-(3x² +2xyz -8xy-7+y²)

=5xyz -5x² +8xy+5-3x² +2xyz -8xy-7+y²

=(5xyz-2xyz)-(5x²+3x²)+(8xy-8xy)+(5-7)+y²

=3xyz-8x²+0+(-2)+y²

N-M=(3x² +2xyz -8xy-7+y²)-(5xyz -5x² +8xy+5)

=3x² +2xyz -8xy-7+y²-5xyz -5x² +8xy+5

=(3x²-5x²)+(2xyz-5xyz)-(8xy-8xy)-(7+5)+y²

=-2x²+(-3xyz)-0-12+y²

M+N = (5xyz-5x² +8xy+5) +(3x² +2xyz-8xy-7+y²)

= 5xyz - 5x² +8xy +5 +3x² + 2xyz - 8xy -7 +y²

= ( 5xyz + 2xyz ) + (-5x² +3x²) + ( 8xy - 8xy ) + ( 5-7) + y²

= 7xyz + (-2x²) + (-2) + y²

M-N = ( 5xyz - 5x² +8xy +5) - ( 3x² +2xyz - 8xy - 7 +y² )

= 5xyz - 5x² + 8xy + 5 -3x² - 2xyz + 8xy + 7 -y²

= ( 5xyz - 2xyz ) + ( -5x² - 3x² ) + ( 8xy+8xy) + ( 5+7) -y²

= 3xyz -(-8x²) + 16xy + 12-y²

N-M = ( 3x² + 2xyz - 8xy -7+y² ) - ( 5xyz - 5x² + 8xy +5)

= 3x² + 2xyz - 8xy - 7+y² - 5xyz+ 5x² - 8xy - 5

=( 3x² + 5x²) + ( 2xyz - 5xyz) + (-8xy - 8xy ) + ( -7-5) + y²

= 8x³ - 3xyz - 16xy - 12+y²

dễ thôi k mik đi rùi mik làm cho

lá sao hả bạn