ax2+cx2-ay+ay2-cy+cy2
= x2(a+c)-y(a+c)+y2(a+c)
= (a+c)(x2-y+y2)
ax2+cx2-ay+ay2-cy+cy2
x2(a+c)-y(a+c)
a+c x2-y+y2
\(ax^2+cx^2-ay+ay^2-cy+cy^2\)
\(=x^2\left(a+c\right)-y\left(a+c\right)+y^2\left(a+c\right)\)
\(=\left(a+c\right)\left(x^2-y+y^2\right)\)