a) (m+7)2+(−m+2)3−3(2−m)(m+2)=
=m2+14m+49+(2−m)3−3(2−m)(2+m)=
=m2+14m+49+8−12m+6m2−m3−3(22−m2)=
=−m3+7m2+2m+57−12+3m2=
=−m3+10m2+2m+45
b) (4−x)3−(x−4)3=
=64−48x+12x2−x3−(x3−12x2+48x−64)=
=64−48x+12x2−x3−x3+12x2−48x+64=
=−2x3+24x2−96x+128
c) (x+2)3−(2x−1)3−6x(3x+1)=
=x3+6x2+12x+8−(8x3−12x2+6x−1)−18x2−6x=
=x3+6x2+12x+8−8x3+12x2−6x+1−18x2−6x=−7x3+9
d) (21x−2)3−(21x+2)3=
=81x3−23x2+6x−8−(81x3+23x2+6x+8)=
=81x3−23x2+6x−8−81x3−23x2−6x−8=−3x2−16
e) (2a+3)3−(2a−3)3−(2a−3)=
=8a3+36a2+54a+27−(8a3−36a2+54a−27)−2a+3=
=8a3+36a2+54a+27−8a3+36a2−54a+27−2a+3=
=72a2−2a+57
f) (b−c)3+(c−a)3+(a−b)3=
=b3−3b2c+3bc2−c3+c3−3ac2+3a2c−a3+a3−3a2b+3ab2−b3=
=−3a2b+3a2c+3ab2−3b2c−3ac2+3bc2=
=3(−a2b+a2c+ab2−b2c−ac2+bc2)
