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Question

anonymous · Answer

TRUE OR FALSE 
The value 5 is an upper bound for the zeros of the function shown below.
f(x_=x^4+x^3-11x^2-9x+18

anonymous · Answer

true

anonymous · Answer

are you 100% sure? how'd you figure it out? @aradhya05

anonymous · Answer

@watchmath whats your take on this?

watchmath · Answer

$f(5)>0$ and $f'(x)>0$ for all $x\geq 5$. Hence $f(x)\geq 0$ for all $x\geq 5$. So all roots of $f(x)$ can't exceed 5.

anonymous · Answer

so that means it's false right? im not actually sure what the upper bound means @watchmath

anonymous · Answer

the upperbound is 4

anonymous · Answer

nt 5 so it is false i m sry for my first ans

anonymous · Answer

ok great thank you guys @aradhya05 can you please give @watchmath a medal and i'll give you a medal, thanks for your help everyone

anonymous · Answer

how to give medal?
i m new here

anonymous · Answer

You click on best answer button

anonymous · Answer

ok thanks

anonymous · Answer

done

anonymous · Answer

thank you for your help, and welcome to the site :)

michele_laino · Answer

please note that your plynomila can be factored as follows:
$$x ^{4}+x ^{3}-11x ^{2}-9x+18=(x+2)(x-1)(x-3)(x+3)$$

anonymous · Answer

Thank you @Michele_Laino  :)

michele_laino · Answer

Thank you! @Frazfootballa