Further Maths Help Watch

Klara_b155
Badges: 9
Rep:
?
#1
Report Thread starter 3 weeks ago
#1
If a quaratic equation has roots (2-i) and (2+i) how do I work out the quadratic equation. I multiplied it out and got 5, but idk where to go from there? Thanks in advance
0
reply
Klara_b155
Badges: 9
Rep:
?
#2
Report Thread starter 3 weeks ago
#2
bumpppppp
0
reply
Your Local Cat
Badges: 17
Rep:
?
#3
Report 3 weeks ago
#3
if \alpha and \beta are roots of a quadratic equation then you could write that equation as

(x-\alpha)(x-\beta)=0 \Leftrightarrow x^2 -(\alpha +\beta)x +\alpha \beta = 0

In your case, your \alpha and \beta are 2+i and 2-i

As you multiplied your two roots, you acquired your "constant" of the quadratic, now you just need the co-efficient of x to complete the equation.
0
reply
Idg a damn
Badges: 15
Rep:
?
#4
Report 3 weeks ago
#4
Or alternatively you can just expand (x-2+i ) (x+2 - i )
Posted on the TSR App. Download from Apple or Google Play
0
reply
Idg a damn
Badges: 15
Rep:
?
#5
Report 3 weeks ago
#5
Sorry it should be (x-2 - i )(x - 2 + i )
Posted on the TSR App. Download from Apple or Google Play
0
reply
Klara_b155
Badges: 9
Rep:
?
#6
Report Thread starter 3 weeks ago
#6
aah i see, thank you! I should have known that, oof I'm tired.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of Birmingham
    Postgraduate Open Day Postgraduate
    Wed, 20 Mar '19
  • King's College London
    Postgraduate Taught Courses - Arts & Sciences - Strand Campus Postgraduate
    Wed, 20 Mar '19
  • University of East Anglia
    All Departments Open 13:00-17:00. Find out more about our diverse range of subject areas and career progression in the Arts & Humanities, Social Sciences, Medicine & Health Sciences, and the Sciences. Postgraduate
    Wed, 20 Mar '19

Where do you need more help?

Which Uni should I go to? (59)
15.21%
How successful will I become if I take my planned subjects? (38)
9.79%
How happy will I be if I take this career? (74)
19.07%
How do I achieve my dream Uni placement? (58)
14.95%
What should I study to achieve my dream career? (43)
11.08%
How can I be the best version of myself? (116)
29.9%

Watched Threads

View All