You are Here: Home >< Maths

# X2 -little bit of help. watch

Announcements
1. yeh, i just checked... it doesn't work for another function i made up, but defo works for this. Browny points to who that can work out why.
2. I got it.... it ll only work if its in the format of

(x - a)^2(x + 2a)

I think....

and

(x + a)^2(x - 2a)
3. (Original post by Frater)
I got it.... it ll only work if its in the format of

(x - a)^2(x + 2a)

I think....

and

(x + a)^2(x - 2a)
You're right it would work if the function was in that form. It would also work if you had:
f(x).(x+a)^n
4. yeh, well we learnt something new today huh? lol

Its because it noly touches the root a and does not intersect, just tried it out on "graph" and it works.
5. (Original post by Frater)
yeh, well we learnt something new today huh? lol

Its because it noly touches the root a and does not intersect, just tried it out on "graph" and it works.
To alaborate on that, any polynomial with discriminant equal to zero will follow your method.

EDIT: I mean a function with a repeated root. Are there discrimants for non-quadratic polynomials?
6. It works for any repeated root, whatever the order. So it would work for, say, (x+1)(x+2)^3, which does actually intersect the x-axis when x = 2.
7. Thats the one.... can't see how this could make maths easier for someone though or help solve an equation, must be some use somewhere.
8. (Original post by DFranklin)
It works for any repeated root, whatever the order. So it would work for, say, (x+1)(x+2)^3, which does actually intersect the x-axis when x = 2.

Yup just checked that on graph and it works. Although not for everyone, it seems that there has to be a and 2a .... if that makes sense
9. (Original post by Frater)
Yup just checked that on graph and it works. Although not for everyone, it seems that there has to be a and 2a .... if that makes sense
Give an example where it doesn't work.
10. (Original post by notnek)
Give an example where it doesn't work.
My bad, jus checked it on graph, it does work.
11. (Original post by Frater)
Thats the one.... can't see how this could make maths easier for someone though or help solve an equation, must be some use somewhere.
The converse is often used to check if a polynomial p(x) has repeated zeros: if it does, then p(x) and p'(x) have a common factor, and you can check for that using the Euclidean algorithm without actually needing to factorise p or p'.
12. Cool, never come across that in A level.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 14, 2008
Today on TSR

### Should I drop out of uni

...to become a pro gamer?

### University open days

• University of Buckingham
Fri, 14 Dec '18
• University of Lincoln
Mini Open Day at the Brayford Campus Undergraduate
Wed, 19 Dec '18
• University of East Anglia
Fri, 4 Jan '19
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams