A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 4 years ago
Find the Complex Roots: 4x3 + 5x2 – x + 2. Thank you!
anonymous
 4 years ago
Find the Complex Roots: 4x3 + 5x2 – x + 2. Thank you!

This Question is Closed

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0try using the quadratic formula

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0alright. let me try this out.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0how would it work considering the first term is cubed, not squared?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Look for a simple substitution that eliminates the quadratic term of 4 x^3+5 x^2x+2. Eliminate the quadratic term by substituting y = x+5/12: 29/12+5 (y5/12)^2+4 (y5/12)^3y = 0

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0how would that help? i don't understand.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0i know it simplifies to 4y3  37y/12 + 2.99.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0do you have an easier way of explaining this?

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0That is definitely not one of the options in this multiple choice question. Let me give the possible answers: (all negative and positive of this number) a. 1, 1/2, 1/4, 2 b. 1, 1/2, 2, 4 c. 1, 1/2, 1/4 d. 1, 1/4, 2

campbell_st
 3 years ago
Best ResponseYou've already chosen the best response.0lol.. wow thats neat work... @pathosdebater

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Is the problem 4x3 + 5x2 – x + 2 or 4*3 + 5*2 – x + 2? (Just making sure)

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0It's exponential, yeah. 4x^3 + 5x^2  x + 2.

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0What? Oh... I didn't know that. I thought it was 4x*3 + 5x*2  x+2

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Sorry for the confusion.

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0This is so strange. I keep getting irrational answers. Is there anything wrong in my calculations which could be causing this?

amriju
 3 years ago
Best ResponseYou've already chosen the best response.0u have an easy way of solving....firstly...note that a cubic eqn has atmost two complex sol..and atleast 1 real soln....so go for the real soln by trial and error...then u hav a factor...divide the polynomial by the factor...u have a quad eqn now as the quotnt....solve it to get the complex roots

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0@pathosdebater I'm not sure, I got similar answers (which is why I came here). There may be a typo in the question (not what I typed; the actual question itself), but no one I know has said anything about it. :\

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0It's not a textbook, it's a practice given by the teacher. (I searched online for duplications but it looks original.)

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Hmm... well there are definitely only 3 roots, so that narrows it down to C and D.

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Thanks for the help though, I'm just going to guess. I appreciate the effort.

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0I got it! It is definitely C

amriju
 3 years ago
Best ResponseYou've already chosen the best response.0do u mind if i say that the options, all of them are wrong..? its so coz...u cant have three complex roots for a REAL cubic eqn...complex roots come in pairs...so...

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0That was my initial guess, but can you explain how?

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.02 is not a complex root

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Let me see if I can try and explain...

amriju
 3 years ago
Best ResponseYou've already chosen the best response.0its got to have two complex roots ..if not zero

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0@amriju I don't mind, I found it to be that way too when I substituted it in. I don't know. Not my practice, it was the teachers. I got all of the other questions on finding zeros, this one was just confusing.

amriju
 3 years ago
Best ResponseYou've already chosen the best response.0have u done complex numbers @pathosdebater

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0Only briefly. I'm not a wizard at them... yet

amriju
 3 years ago
Best ResponseYou've already chosen the best response.0u really cant have an option with more than two values...that settles it...as for the solution u got to try this way...if a,b,c be the roots then\[\sum_{?}^{?} a=5/4...\sum_{?}^{?} ab=1/4....abc=2/4=1/2\]
Ask your own question
Sign UpFind more explanations on OpenStudy
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.