Polynomial Question ~ (1 Viewer)

[Aysce]

The polynomial has a zero at x = 1. Find k hence, factorise P(X).

Originally I found K as -9 as I subbed in x=1 and let P(1) = 0, but when I factorised it, it didn't come with the right answer so yeahh.. Anyways answer is

P(X) = (x-1)(x-7)(x+2)

Nothing like maths on a friday night.. :L

 

[nightweaver066]

The polynomial has a zero at x = 1. Find k hence, factorise P(X).

Originally I found K as -9 as I subbed in x=1 and let P(1) = 0, but when I factorised it, it didn't come with the right answer so yeahh.. Anyways answer is

P(X) = (x-1)(x-7)(x+2)

Nothing like maths on a friday night.. :L

Since it has a zero at x = 1,



Now the polynomial is,

When you divide through by (x-1), you should end up with

Check your working out in your long division.

 

[RivalryofTroll]

(1)^3 - 6(1)^2 + k + 14 = 0
k + 9 = 0
Therefore, k = -9
P(1) = 0
Therefore, x-1 is a factor.

x^3 - 6x^2 -9x + 14 Divide By x-1

P(x) = (x-1)(x^2 - 5x - 14)
Therefore, P(x) = (x-1)(x-7)(x+2) is correct.
Answer should be correct
I'm in Year 10 so don't trust me 100%

 

[RivalryofTroll]

Since it has a zero at x = 1,



Now the polynomial is,

When you divide through by (x-1), you should end up with

Check your working out in your long division.

Yeah this

 

[Aysce]

DAYUM i forgot about (x-1) :L Brain fart :L Thanks guys btw Troll, you're accelerated I assume?

 

[RivalryofTroll]

DAYUM i forgot about (x-1) :L Brain fart :L Thanks guys btw Troll, you're accelerated I assume?

Nah, my teacher at school just goes really fast... I'm doing Year 10.3 for Maths just like most schools...
We already covered Circle Geo and Polynomials + Curve Sketching in the past weeks.... We're doing like Functions and Logarithms now..

 

[Aysce]

Hmm this is the first time I've learnt polynomials O.O

 

[SpiralFlex]

Hmm this is the first time I've learnt polynomials O.O

It's not stage 5.3. However, some schools prepare you for some Year 11 topics. Example, logarithms are "assumed."

 

[Aysce]

So it's essential to know logs? :S My school barely did logs

 

[RivalryofTroll]

Hey Spiral, are relation of roots in Year 11 Polynomials?
Like sum of roots for a polynomial of degree = 3 is -b/a?
Product of roots is -d/a?

 

[RivalryofTroll]

So it's essential to know logs? :S My school barely did logs

In Year 10, I think you just do things like applying the laws/rules of logs + using the change of base rule?
Then, I think you learn about sketching logs in Year 11 I'm assuming, not sure...

EDIT: Of course, there's more to it but yeah...

 

[SpiralFlex]

Hey Spiral, are relation of roots in Year 11 Polynomials?
Like sum of roots for a polynomial of degree = 3 is -b/a?
Product of roots is -d/a?

Yes. However, some schools choose to do it in Year 12. (Some.) But generally yes.