Inequalities and functions, please help.

[scottw]

Hello, I am having trouble with a couple things. First solving the inequality:
2x^5 < than or = to 256x - 511x^3
I have it factored down to (x^2+256)(2x^2-1) but i dont know what to do next.

Also I need to figue out this question: At 15 degrees there is 76 chirps per a minutes, and at 19 degrees there is 100 chirps per minute. Write the number of chirps as a function of the temperature.

I dont know what to do there. Please help me. Thanks.

 

[royhaas]

Actually it is equivalent to \(\displaystyle x(2x^2-1)(x^2+256) \le 0\). Since the last factor is always positive, this leaves you to consider the other cases, since one factor must be positive and the other negative in order for the product to be negative.

Don't forget to check your results.