Let ‘E’ be the required expression. Then, we have
x2−xy+y2−x+y+3−E=−x2+3y2−4xy+1
Therefore,E=(x2−xy+y2−x+y+3)−(−x2+3y2−4xy+1)
=x2−xy+y2−x+y+3+x2−3y2+4xy−1
Collecting positive and negative like terms together, we get
x2+x2−xy+4xy+y2−3y2−x+y+3−1
=2x2+3xy−2y2−x+y+2