Can anyone help! My h/w is due in 1hr time thanks Evaluate the following limits

lim(√x^4-1x^3+1)/(9x^2-9)
x-inf

lim(√x^4-1x^3+1)/(9x^2-9)
x--inf

Question

Can anyone help! My h/w is due in 1hr time thanks Evaluate the following limits 

lim(√x^4-1x^3+1)/(9x^2-9)
x->inf

lim(√x^4-1x^3+1)/(9x^2-9)
x->-inf

dumbcow · Answer

use the fact that limit of 1/x = 0 as x->infinity

multiply top and bottom by 1/x^2, note that 1/x^2 = 1/sqrt(x^4)

dumbcow · Answer

did that help? what did you get?

anonymous · Answer

hmm i'm still trying to solve it...:)

anonymous · Answer

I'm so confused

dumbcow · Answer

also i should mention, the 2 limits will be the same
limit of 1/x = 0 as x->+-infinity, doesn't matter if its positive or neg

dumbcow · Answer

ok after multiplying by 1/x^2 on top and bottom you should get

--> (sqrt(1-1/x +1/x^4)) / (9-9/x^2)

anonymous · Answer

is that the answer? or ?

dumbcow · Answer

really :), the limit usually is a number not an expression
i assumed you can do it from here any expression of the form a/x^n when taking the limit x->infinity is zero
apply those limits to the above function, then whats left over?

anonymous · Answer

Thanks for your help!