Step-by-step explanation:
x³ - 4x² - 25x + 100k
= x²(x - 4) - 25(x - 4k)
= (x² - 25)(x - 4k)
= (x + 5)(x - 5)(x - 4k)
Hence the other 2 zeroes are x = -5 or x = 5.
