Rút gọn biểu thức
a, A = (3 x - 3).(x - y) + ( x + y ).( 4x - y)
b, B = (12x - 5).( 4x - 1) + ( 3x - 7).( 1-16x ) -81
c, C= ( x - 5 ).( 2x + 3) - 2x ( x - 3 ) + x + 7
d, D = ( x + 3 ).( x - 3 ) - ( x + 4 ).( x + 1 )
e, E = ( x - 5 ) ^2 + ( y + 5 ) ^2 + 2( x - 5 ).( y + 5 )