Could someone help me do this? :/ I need to use the rational root thereon

Question

lifeisadangerousgame · Answer

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solomonzelman · Answer

I just learn this staff from hartnn, yesterday.

lifeisadangerousgame · Answer

Cool

solomonzelman · Answer

Connection snapped.

solomonzelman · Answer

$$x^3+2x^2+2x-21=0$$
so the POSSIBLE roots are going to be,$$\huge {\color{blue} {±1,±3,±7,±21} }$$

solomonzelman · Answer

Plug each in, to see if it works

solomonzelman · Answer

Should we pug them in together?

directrix · Answer

@SolomonZelman   I think there is supposed to be a coefficient of 9 for the x^3 term.

lifeisadangerousgame · Answer

I think I've got it, I've been re-reading the book and I think I know what I'm doing, I checked it with the answer key. Thank you for helping guys!

solomonzelman · Answer

Anytime!

solomonzelman · Answer

I did kind of get confused, looking over and over, and seeing that none of the numbers actually work as the roots.

solomonzelman · Answer

Yes, ofcourse, coefficient of x^3 is 9.
My bad...
$\huge {\color{purple} {Good} }$    $\huge {\color{purple} {evening!} }$