Which of the following is a polynomial with roots 5, 7, and −8?
f(x) = x3 − 35x2 − 56x + 61
f(x) = x3 − 35x2 − 61x + 280
f(x) = x3 − 4x2 − 35x + 56
f(x) = x3 − 4x2 − 61x + 280

- anonymous

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- anonymous

@MrNood @OregonDuck

- OregonDuck

f(x) = (x-5)(x-7)(x+8) = (x-5)(x^2+x-56)
= x^3+x^2-56x-5x^2-5x+280
f(x) = x^3-4x^2-61x+280
So the answer is d

- anonymous

how did you do that so fast

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## More answers

- anonymous

are you super man?

- OregonDuck

cause this stuff is easy

- OregonDuck

i can do pre calculus in 7th grade

- OregonDuck

i am only 12 fyi

- anonymous

so you are super man

- anonymous

mind helping me with one more

- MrNood

however - @OregonDuck all oyu have given the poster is the knowledge that YOU can solve this question
what iwould be truly helpful would be to show HOW to solve it - then let HIM do the work
you learn better by DOING than by watching

- OregonDuck

sure :)

- anonymous

Which of the following is a polynomial with roots 4, 2i, and −2i?
f(x) = x3 − 4x2 + 8x − 4
f(x) = x3 − 8x2 + 16x − 4
f(x) = x3 − 4x2 + 4x − 16
f(x) = x3 − 4x2 + 8x − 16

- MrNood

wait!

- OregonDuck

WHAT?!?

- MrNood

if the roots are a,b & c then the factors are
(x-a)(x-b)(x-c)
if you put your three roots into that formula then mutiply out the 23 brackets you will come to the answer YOURSELF

- OregonDuck

Work backwards for each root to get the factor..
(x - 4)(x - 2i)(x + 2i)
Distribute..
(x - 4)(x² - 4i²)
= (x - 4)(x² + 4) [Noting that i² = -1]
= x³ - 4x² + 4x - 16 [A]

- MrNood

if the roots are a,b & c then the factors are
(x-a)(x-b)(x-c)
if you put your three roots into that formula then mutiply out the 3 brackets you will come to the answer YOURSELF

- anonymous

ya i got that to

- OregonDuck

it is a

- OregonDuck

wait no it is c sorry i was reading mine post i put a for some reason lol

- MrNood

@OregonDuck
Once again - juist showing that YOU know how to do this type of questin.
LET the poster do some of the calculation - he will actually LEARN from that instead of copying

- anonymous

im working it out as well mrnood

- OregonDuck

he will learn my failing the dba or segment exams cause you need your notes and memory to help you

- anonymous

i am taking these problems down as notes

- anonymous

so i can learn to do the harder ones

- OregonDuck

EXACTLY SEE ^^^^^^^^

- MrNood

but until you do one yourself you will not be sure that oyu UNDERSTAND how to do it
you do not need to learn 'harder' questions - you need to learnt the METHOD - then oyu can do ALL questions

- anonymous

i did 8 out of the 10 of my practice questions @MrNood but just needed help for these two

- OregonDuck

FINE ASK HIM FOR HELP NOT ME AL LEAST I SHOWED MY WORK!!!!!!!

- anonymous

Please dont fight @OregonDuck and @MrNood

- MrNood

Don't get in a sulk
Just try to help posters to learn rather than going right through to tthe answer

- anonymous

thank you @MrNood and @OregonDuck

- OregonDuck

yeah your welcome

- MrNood

YOU'RE welcome

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