Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
DeadShot
Group Title
Which of the following is a polynomial with roots  square root of 5, square root of 5, and 3 ? x3  2x2  3x + 6, x3 + 2x2  3x  6, x3  3x2  5x + 15, or x3 + 3x2  5x  15?
 one year ago
 one year ago
DeadShot Group Title
Which of the following is a polynomial with roots  square root of 5, square root of 5, and 3 ? x3  2x2  3x + 6, x3 + 2x2  3x  6, x3  3x2  5x + 15, or x3 + 3x2  5x  15?
 one year ago
 one year ago

This Question is Closed

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
If you have roots of: a, b, and c your polynomial has the form: (x  a)(x  b)(x  c) = 0 Substitute a, b, and c for the given roots and multiply the expression out on the left side.
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
x^3 2.25x^2+2.25x^23x22.25x+2.25x3x15
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
simplified, it's x^33x^23x15, right?
 one year ago

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
You wouldn't even have to ask that last question because you have 4 choices and this choice is not even listed among them. Here's a hint on how to expand that expression I gave you: (x  a)(x  b)(x  c) = 0 [(x  a)(x  b)](x  c) = 0 [x^2  (a + b)x + ab](x  c) = 0 [x^2  (a + b)x + ab]x  [x^2  (a + b)x + ab]c = 0
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
[x^2(2.25+2.25)x + (2.25)*2.25]x[x^2(2.25+2.25)x + (2.25)*2.25]3=0
 one year ago

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
Where are you getting +2.25 from? Neither has anything to do with sqrt(5).
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
sqrt(5) is approx 2.25
 one year ago

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
You don't want to be working with approximations here.
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
x^3  3x^2  5x + 15
 one year ago

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
I would suggest evaluating the following first: [x  sqrt(5)][x + sqrt(5)] That correspond to the leftmost factors. Get that down to a trinomial.
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
that would be x^25
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
(x^25) (x3)=x^3  3x^2  5x + 15
 one year ago

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
The third root is "3", so you have: [x  (3)] or (x + 3) for that third factor. I think that's where you having your trouble. When you subtract a negative, it's like adding a positive.
 one year ago

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
So, taking up from where you were writing: (x^2  5)(x + 3) = 0 And then expand that. You are very close to your answer now.
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
so, it's x^3+3x^25x15?
 one year ago

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
Yes! Excellent! Just remember about subtracting negatives and you will be ok.
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
Okay, Thanks for the help!
 one year ago

tcarroll010 Group TitleBest ResponseYou've already chosen the best response.1
You're welcome! Good luck to you in all of your studies and thx for the recognition! @DeadShot
 one year ago

DeadShot Group TitleBest ResponseYou've already chosen the best response.0
No problem!
 one year 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.