Differentiation help plz

on the 3rd line to the 4th, how does the denominator completely remove 4-2 to leave it with only t+1/t^2?

on the 3rd line to the 4th, how does the denominator completely remove 4-2 to leave it with only t+1/t^2?

There is a mistake.

Revised 3rd line:

=\frac{1-\frac{1}{t}}{\sqrt{(1+\frac{1}{t})^2}}

I see no reason for it to do so, unless 2+t^2 = t; is there some context missing?
ETA: still don't see a reason for it…

(edited 10 years ago)

don't worry! I figured it out

sqrt(4+t^2-2+(1/t^2))
turns into
sqrt (t^2+2 +(1/t^2))
so sqrt ((t+1/t^2))
= t+(1/t)

(edited 10 years ago)

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