Which of the following is one of the factors of
(x4+x2−20)
(x2−5)
(x2+4)
(x−4)
(x2+5)
Let x2=t
⇒t2+t−20
⇒t2+5t−4t−20
⇒t(t+5)−4(t+5)
⇒(t+5)(t−4)
Substituting the value of t
⇒(x2+5)(x2−4)
⇒(x2+5)(x−2)(x+2)
The factors of x4+x2+25 are