This question of my homework was pretty much exactly like the one before it, except with different numbers. Got the previous one, but I'm stuck on this one. Can't get any farther than this:

Find the max and min values of the function s(t) = ln((t2 +1)/(t2-1)) + 6lnt, t is greater than or equal to 1.1 or less than or equal to 10.

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Broke it up using ln rules:

s(t) = ln(t2+1) - ln(t2-1) + 6lnt

s(1.1) = 2.926

s(10) = 13.836

s'(t) = (2t/t2+1) - (2t/t2-1) + 6t

Simplifying gives me this:

s'(t) = (6t4 - 4t2 -6)/(t5-t)

I'm supposed to set it to zero:

0 = 6t4 - 4t2 - 6

But what do I do from there? How do I factor a quartic?