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Mathematics 7 Online
zarkam21:

Same type of question

zarkam21:

1 attachment
zarkam21:

okay so for part I I got +-1,+-,2,+-3,+-4,+-6,+-12

zarkam21:

then for part II i got 1

zarkam21:

am i on the right track so far?

Vocaloid:

the root 1 does not produce a remainder of 0 after synthetic division so you will have to ry another root

zarkam21:

2

Vocaloid:

not quite, check your calculations again if you plug in the root into the equation it should equal 0

Vocaloid:

to speed this process up you can use a calculator to start plugging in x values and see which ones give you 0, starting with 1 or -1, then 2 and -2, etc. until you get 0

Vocaloid:

silly if you're reading this is there an easier way to narrow down the possible roots w/o using calculus

zarkam21:

okay so zero for part II

zarkam21:

@sillybilly123

Vocaloid:

0 is not a possible root (it is not in your list of rational roots)

Vocaloid:

\(\color{#0cbb34}{\text{Originally Posted by}}\) @zarkam21 okay so for part I I got +-1,+-,2,+-3,+-4,+-6,+-12 \(\color{#0cbb34}{\text{End of Quote}}\) ^ your root must be one of these

zarkam21:

4

Vocaloid:

when you plug in x = 4, your result is not 0 so keep trying

zarkam21:

i got it

zarkam21:

its 3

Vocaloid:

good for part III) divide the function by (x-3) and write the resulting function

zarkam21:

x^3+4x^2+6x+4

Vocaloid:

awesome, then for part IV try to find another root by testing the possible roots from part I

zarkam21:

1 attachment
Vocaloid:

good, now try testing these roots to see if you can find another solution

zarkam21:

so just substitute for x right

Vocaloid:

yes

zarkam21:

into the cubic function right not the original

Vocaloid:

yes (technically both will work but cubic is easier)

zarkam21:

I'm getting 15,40,85

zarkam21:

Am i on the right track

Vocaloid:

what did you do to obtain these values?

zarkam21:

1 attachment
zarkam21:

oh i have to set them equal to zero

Vocaloid:

if you are plugging in roots, keep going until the result is 0

zarkam21:

oh okY

zarkam21:

-2?

Vocaloid:

good, so -2 is the other root so that's your answer for IV

zarkam21:

OKAY SO for part V it would just be x=-1,+-i,-2

Vocaloid:

part V is not in the original screenshot

zarkam21:

PArtV use the quadratic formula to find the final 2 roots

Vocaloid:

after you divide the cubic polynomial by (x+2) what polynomial do you get?

zarkam21:

x^2+2x+2

Vocaloid:

good, now apply the quadratic formula to get the last two roots

zarkam21:

x=-1+i

Vocaloid:

good but don't forget the other one x = -1 - i (remember the quadratic formula has a +/- sign) and that's it

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