Question

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

Answer 1

@MrNood @OregonDuck

Answer 2

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

Answer 3

how did you do that so fast

Answer 4

are you super man?

Answer 5

cause this stuff is easy

Answer 6

i can do pre calculus in 7th grade

Answer 7

i am only 12 fyi

Answer 8

so you are super man

Answer 9

mind helping me with one more

Answer 10

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

Answer 11

sure :)

Answer 12

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

Answer 13

wait!

Answer 14

WHAT?!?

Answer 15

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

Answer 16

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]

Answer 17

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

Answer 18

ya i got that to

Answer 19

it is a

Answer 20

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

Answer 21

@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

Answer 22

im working it out as well mrnood

Answer 23

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

Answer 24

i am taking these problems down as notes

Answer 25

so i can learn to do the harder ones

Answer 26

EXACTLY SEE ^^^^^^^^

Answer 27

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

Answer 28

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

Answer 29

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

Answer 30

Please dont fight @OregonDuck and @MrNood

Answer 31

Don't get in a sulk

Just try to help posters to learn rather than going right through to tthe answer

Answer 32

thank you @MrNood and @OregonDuck

Answer 33

yeah your welcome

Answer 34

YOU'RE welcome