Why does √(4t² + 4t⁴ + 1) simplify to 2t² + 1?

[ProPatto16]

in an example I've got in a textbook it shows this

<2t,2t²,1>
sqrt(4t²+4t⁴+1)

becomes

<2t,2t²,1>
2t²+1


how?

 

[cragar]

they factored the bottom part and then took the square root .

 

[HallsofIvy]

$$\sqrt{a^2}= |a|$$
and $2t^2+ 1$ is never negative.