Question

Factorise:x^4+4

Answer 1

x^4 + 4

= (x^4 + 4x^2 + 4) - 4x^2

= (x^2 + 2)^2 - (2x)^2

= [(x^2 + 2) - 2x][(x^2 + 2) + 2x]

= (x^2 - 2x + 2)(x^2 + 2x + 2)

hope this helped