Question

giúp mk nha mk đang cần gấp!!

Answer 1

Bài 4: 

a: \(A=2x^4+3x^3-5x^2+2x+5\)

\(B=x^4+3x^3-6x^2+2x+1\)

b: \(A+B=3x^4+6x^3-11x^2+4x+6\)

\(A-B=x^4+x^2+4\)

c: \(A-B=x^4+x^2+4>=4>0\forall x\)

Answer 2

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

\(A-B=x^3-3x^2y+2xy^2-5y^3-x^2y+2xy^2-4x^3+x^2y-2xy^2-y^3+2x^3+4xy^2=-x^3-6y^3-3x^2y+6xy^2.\)