IV.Hallar la diferencia obtenida al restr la segunda expresion de la primera
1.3xy-2xz+4zx ;3zx+yz-2xy R.5xy-3yz+zx
2.4x^2+3y^3-6x+4y-2 ;2x-y^2+3x^2-4y+3 R.x^2+4y^2-8x+8y-5
3.-3xy^4-8x^3 y^2-19y^5+18 ;x^5-x^2 y^3+6xy^4+25y^5 R.- x^5-8x^3 y^2+x^2 y^3-9xy^4-44y^5+18
4. 3/5 x^4+3/4 x^3 y-5/7 xy^3+2/3 y^(4 );x^4+5/8 x^2 y^2-1/3 xy^3+5/6 y^4 R.-2/5 x^4+3/4 x^3 y-5/8 x^2 y^2-8/21 xy^3-1/6 y^4
5. 3/10 m^4 n^2-3/7 m^2 n^4+5/9 n^6 ; -2/13 m^6+1/3 n^6-7/20 m^4 n^2+5/15 m^4 n^2-3/5
R. 2/13 m^6+13/20 m^4 n^2-11/14 m^2 n^4+2/9 n^6+3/5
