Answer:
y (x² + 1) (x² - 5)
Step-by-step explanation:
Take 'y' from each term.
x⁴y - 4x²y - 5y = y[x⁴ - 4x² - 5]
Now factorize x⁴ - 4x² - 5.
Sum = -4
Product = -5
Factors = -5 , 1
When we add (-5) + 1, it gives (-4) and when we multiply (-5)*1, gives (-5).
x⁴ - 4x² - 5 = x⁴ + x² - 5x² - 5
= x²(x² + 1) -5(x² + 1)
= (x²+ 1) (x² - 5)
x⁴y - 4x²y - 5y = y (x² + 1) (x² - 5)