a) (m - n) (m + n) = m2 + mn - mn + n2 = m2 + n2
b) x(a - b) - x(a + b) = ax - bx - ax - bx = -2bx
c) (a2 - ax + by) - (by - a2 - ax) = a2 - ax + by - by + a2 + ax = 2a2
d) (a - b) (a + b) - (b - a)b = a2 + ab - ab - b2 - b2 + ab = a2 - 2b2 + ab
a) (m-n)(m+n)=m2 +mn-mn-n2 =m2 -n2
b) x(a-b)-x(a+b)=ax-bx-ax-bx=-2bx
c) (a2 -ax+by)-(by-a2 -ax)=a2 -ax+by-by+a2 +ax=2a2
d) (a-b)(a+b)-(b-a)b=a2 +ab-ab-b2-b2 +ab =a2 -2b2 +ab