Help with Inequality: x(x^(2)+4)≥0

Help with Inequality: x(x^(2)+4)≥0

Postby Guest » Mon Sep 09, 2019 2:33 pm

I got stuck trying to solve it. :( I wold really appreciate your help.

Solve the Inequality: x(x^(2)+4)≥0
Guest
 

Re: Help with Inequality: x(x^(2)+4)≥0

Postby Guest » Tue Oct 08, 2019 10:40 am

Positive times negative is negative so we don't want that case.
Positive times positive is positive and negative times negative is positive.
But [tex]x^2+ 4[/tex] is never negative so x must be non-negative.

Another way of thinking about this is that dividing both sides of an inequality by a positive number does not change the direction of the inequality. So dividing both sides of [tex]x(x^2+ 4)\ge 0[/tex] by the positive number [tex]x^2+ 4[/tex] gives [tex]x\ge 0[/tex].
Guest
 

Re: Help with Inequality: x(x^(2)+4)≥0

Postby HallsofIvy » Mon Dec 23, 2019 11:12 am

You should also note that [tex]x^2+ 4[/tex] cannot be 0.

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