theorem Th6: :: POLYEQ_5:6

for a, b being Complex holds (a - b) |^ 4 = ((((a |^ 4) - ((4 * (a |^ 3)) * b)) + ((6 * (a |^ 2)) * (b |^ 2))) - ((4 * (b |^ 3)) * a)) + (b |^ 4)