Question

x^4 - x^2 + 4 factorise

Answer 1

x^4 + 4-x^2 

by identity a^2 - b^2 

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

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

OR 

x^4 - x^2 +4

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

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

i hope this will help




- by ABHAY