Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
Mimi_x3
Group Title
The polynomial P(x) = x^3  2x^2 + kx + 24 has roots a , b and γ
(i) It is known that two of the roots are equal in magnitude but opposite in sign.
Find the third root and hence find the value of k
Can you please help .
 3 years ago
 3 years ago
Mimi_x3 Group Title
The polynomial P(x) = x^3  2x^2 + kx + 24 has roots a , b and γ (i) It is known that two of the roots are equal in magnitude but opposite in sign. Find the third root and hence find the value of k Can you please help .
 3 years ago
 3 years ago

This Question is Closed

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.0
:@ ?? why yu angry ? LOL
 3 years ago

aredsani Group TitleBest ResponseYou've already chosen the best response.0
3rd root is 2
 3 years ago

oktalBlizzard Group TitleBest ResponseYou've already chosen the best response.0
not angry
 3 years ago

oktalBlizzard Group TitleBest ResponseYou've already chosen the best response.0
just having a bad day
 3 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.0
how is 3rd root 2 ?
 3 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.0
lols , having a bad day ? why ?
 3 years ago

oktalBlizzard Group TitleBest ResponseYou've already chosen the best response.0
I passed the entry test to uni, but apparently, I need to get minimum of 2 A levels to get into it. A levels take 2 years to get. I have 4 months.
 3 years ago

estudier Group TitleBest ResponseYou've already chosen the best response.1
I got so far (for roots a,a and c) 3a +c = 2 and a^2 c = 24 U get that?
 3 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.0
w8 , what's c ?
 3 years ago

estudier Group TitleBest ResponseYou've already chosen the best response.1
I don't mean understand, I mean u calculated same?
 3 years ago

estudier Group TitleBest ResponseYou've already chosen the best response.1
I said for roots, a,a and c
 3 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.0
ohh lols , i dnt even know how to do it
 3 years ago

estudier Group TitleBest ResponseYou've already chosen the best response.1
There is similar (not same) formula like Vieta for cubic as for quadratic....
 3 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.0
What's Vieta ?
 3 years ago

estudier Group TitleBest ResponseYou've already chosen the best response.1
Formulae for sum and product of roots of quadratic.
 3 years ago

jimmywhoaaw Group TitleBest ResponseYou've already chosen the best response.0
Let a be the first root >0. Then b=a Now since a cubic function with 3 real roots then must be of the form: (xa)(xb)(xv)= x^3  2x^2 + kx + 24 But b=a so LHS is (xa)(x+a)(xv)=(x^2a^2)(xv) Multiplying the left hand side out we get: =x^3v*x^2a^2*x+v*a^2=P(x) From this we see that v=2 which implies 24=2*a^2 then a^2=12 but a^2*x=kx thus k=12
 3 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.0
thank you (:
 3 years ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.