Factor.
t^4 + 2t^2 + 1
t^4 + 2t^2 + 1

Remember that (a+b) = a^2 + 2ab + b^2.
Hence:
t^4 + 2t^2 + 1 = (t^2+1)^2
In this case:
a = t^2 and b = 1.
Hence:
t^4 + 2t^2 + 1 = (t^2+1)^2
In this case:
a = t^2 and b = 1.

(t^2+1)(t^2+1)

(t^2 + 1)^2

t^4 + 2t^+1=(t^2+1)^2

Yup