Question:` a^4 - 27a^2 + 1`
Answer
`a^4 - 27a^2 + 1 = (a^2)^2 - 2.a^2.1 + (1)^2 - 25a^2`
` = (a^2 - 1)^2 - (5a)^2`
`= {(a^2 - 1) + 5a} {(a^2 - 1) - 5a}`
`= (a^2 + 5a - 1) (a^2 - 5a - 1)` (Ans)