(a-b)2=a2-2ab+b2
(4-b)2=±
±
b
±
b2
(a-7)2=±
a2±
a
±
(4a-b)2=±
*
2
±
*
*b
±
b2
(a-7b)2=±
a2±
*a*
+
*
2
(4-t)2=±
±
8t±
t2
(4-t)*(4-t)=±
±
8t±
t2
(t-4)*(4-t)=±
t2±
8t±
(15-z)*(15-z)=±
±
z
±
z2
(x-6)*(6-x)=±
x2±
x
±
(15ax-bz)*(15ax-bz)=±
*(
)2
±
*
*bz
±
(bz)2
(vt-6up)*(6up-vt)=±
(vt)2±
*vt*
±
*(
)2
(6-z)*(6-z)=±
±
z
±
z2
(4-x)*(x-4)=±
x2±
x
±
(6x-bz2)*(6x-bz2)=±
*(
)2
±
*
*bz2
±
(bz2)2
(15dp-t)*(t-15dp)=±
t2±
*t*
±
*(
)2