A= (0,5x²+3,5xy+3)-(2,7x²+1,75+1,3xy)-(1,25+2,2xy-3,2x²)
=
= 0,5x²+3,5xy+3-2,7x²-1,75-1,3xy-1,25-2,2xy+3,2x²
=
=0,5x²-2,7x²+3,2x²+3,5xy-1,3xy-2,2xy+3-1,75-1,25 =
=3,7x²-2,7x²+3,5xy-3,5xy+3-3 =
=x²
A=(4x²-9+3y²)-(3x²+2y²)+(14-y²) =
=4x²-9+3y²-3x²-2y²+14-y² =
=x²-9+14 =
=x²+5=
=x²+(√5)²