(2,4x2 + 1,7y2 +2xy) - (0,4x2 -1,3y2 +xy)
= 2,4x2 + 1,7y2 +2xy - 0,4x2 +1,3y2 -xy
= (2,4x2 - 0,4x2 ) + (1,7y2 + 1,3y2 ) +(2xy - xy)
=2x2 + 3y2 +xy
(2,4x2 + 1,7y2 +2xy) - (0,4x2 -1,3y2 +xy)
=`2,4x^2+1,7y^2+2xy-0,4x^2+1,3y^2-xy`
`=(2,4x^2-0,4x^2)+(1,7y^2+1,3y^2)+(2xy-xy)`
`=2x^2+3y^2+xy`