Question

The change in water level of a lake is modeled by a polynomial function, W(x). Describe how to find the x-intercepts of W(x) and how to construct a rough graph of W(x) so that the Parks Department can predict when there will be no change in the water level. You may create a sample polynomial to be used in your explanations.

Answer 1

@Destinymasha hey do you think you could help me with this question....this is the whole question there is no data no nothing

Answer 2

@annas @waleomolola2009 @Warped_909 @Rolltideroll @Muskan @LegoMyEgo @youngstar10

Answer 3

@hba @HelpBlahBlahBlah @eliassaab

Answer 4

@fskapex123 @helder_edwin @lexinicole @mangorox

Answer 5

to find the x-intercepts just solve the equation W(x)=0.
Regarding the graph, it would depend on the polynomial.

Answer 6

idk stilll what to do @helder_edwin

Answer 7

well the question is kind of silly.

u can give yourself a polynomial (not a very difficult one) and solve W(x)=0, then explain how would u draw its graph. I think a cubic polynomial would be a good choice.

Answer 8

yea here is my polynomial i came up with \[2x ^{3}+3x ^{2}-x-4\]

Answer 9

no how would i solve for w(x)=0

Answer 10

u can use synthetic division

Answer 11

so would i have to use 0?

Answer 12

for the outside number

Answer 13

no idea (sorry i don't know how u r taught this in your country)

Answer 14

well do you know anybody that could help me with this question

Answer 15

or do you think you could help me with another question

Answer 16

i just solved the polynomial u wrote, it has one real root and two complex roots.

try another one!!

Answer 17

ummm.....why do i have to try another one

Answer 18

and how did you solve it

Answer 19

i solved it using a calculator. (it is faster)

having only one real root seems pointless to the excercise.

Answer 20

ok \[5x ^{3}+10x ^{2}-x-15\]

Answer 21

also complex roots.

try the other way around: say u want your roots to be 5 ,12 and 25 (or whichever numbers you like) so your polynomial would be
\[ f(x)=(x-5)(x-12)(x-25) \]
multiply out this and u got your polynomial

Answer 22

ok hold on solving it now

Answer 23

this is what i got \[x ^{3}-42x ^{2}+485x+1500\]

Answer 24

yes

Answer 25

ok so how does this answer my question

Answer 26

ok. the x-axis would be the time (says weeks of the year) so x=5, x=12 and x=25 r the weeks of the year when the waterlevel does not change

Answer 27

ok

Answer 28

the graph is this

http://www.wolframalpha.com/input/?i=plot+x^3%E2%88%9242x^2%2B485x-1500

Answer 29

i thought you was suppose to see why it the equation equals 2 zero

Answer 30

i don't understand

Answer 31

look at the question