a:
\(A=10-2y-\dfrac{5}{3}x^4y^3+4x^2y^2+4x-4y-\dfrac{10}{3}x^4y^3+x-11x^2y^2\)
\(=\left(-\dfrac{5}{3}x^4y^3-\dfrac{10}{3}x^4y^3\right)+\left(4x^2y^2-11x^2y^2\right)+\left(4x+x\right)+\left(-2y-4y\right)+10\)
\(=-5x^4y^3-7x^2y^2+5x-6y+10\)
Bậc là 7
\(B=\dfrac{1}{2}y-3x^2y^3-3x-3x^4y^3+1-2x+\dfrac{11}{2}y+1+8x^4y^3\)
\(=\left(-3x^4y^3+8x^4y^3\right)+\left(-3x-2x\right)+\left(\dfrac{1}{2}y+\dfrac{11}{2}y\right)+\left(1+1\right)-3x^2y^3\)
\(=5x^4y^3-5x+6y-3x^2y^3+2\)
Bậc là 7
b: Khi x=1;y=1 thì \(A=-5\cdot1^4\cdot1^3-7\cdot1^2\cdot1^2+5\cdot1-6\cdot1+10\)
=-5-7+5-6+10
=-7-6+10=-3
Khi x=1;y=1 thì
\(B=5\cdot1^4\cdot1^3-5\cdot1+6\cdot1-3\cdot1^2\cdot1^3+2\)
=5-1+6-3+2
=3+2=5
c: P=A+B
\(=-5x^4y^3-7x^2y^2+5x-6y+10+5x^4y^3-5x+6y-3x^2y^3+2\)
\(=-7x^2y^2+5x^4y^3-3x^2y^3+12\)
Q=A-B
\(=-5x^4y^3-7x^2y^2+5x-6y+10-5x^4y^3+5x-6y+3x^2y^3-2\)
\(=-10x^4y^3+3x^2y^3-7x^2y^2-5x^4y^3+10x-12y+8\)
d: \(M:\left(\dfrac{3}{5}x^2y\right)=B\)
=>\(M=\left(5x^4y^3-5x+6y-3x^2y^3+2\right)\cdot\dfrac{3}{5}x^2y\)
=>\(M=3x^6y^4-3x^3y+\dfrac{18}{5}x^2y^2-\dfrac{9}{5}x^4y^4+\dfrac{6}{5}x^2y\)
