Here's the question you clicked on:
Jusaquikie
lim x → infinity arctan(x^4 − x^6)
i tried the squeeze but still not sure what to do with -pi/2 < arctan(x^4(1-x^2) <pi/2
For large x, x^6 completely dominates over x^4 so the argumant of arctan will tend toward negative infinity. Therefore the limit you are seeking is -pi/2. http://fooplot.com/plot/oopgxdk0vi