Confused!!

[needmadhelp]

i have to change these 3rd degree polynomials to 4th degree AND group factor it . Any help given would be GREATLY appreciated. thank you. show work if you can please

k^2-13k+40



12x^3+9a^2-30a



4x^2-23x+15



8x^2+28x-60

 

[Mrspi]

What does the problem say exactly?

I am guessing at the problem, and my guess leads to a somewhat weird, but perhaps clever, problem. If the problem says to turn these expressions into polynomials of the fourth degree and factor them (not quite sure what "group factor" means), then you are looking for a substitution that leads to a factorable polynomial of the fourth degree. I'll do the first for you. Then you are on your own.

Let k = m^2.

Then k^2 = m^4.

k^2 - 13k + 40 = m^4 - 13m^2 + 40 = (m^2 -5)(m^2 - 8).

I really HATE to guess at what a problem is, or what the directions are.

That said, I'm wondering if the "job at hand" is to re-write the given THREE-TERM expression as an expression with FOUR TERMS, and then factor by grouping.

For example, if the problem was

x² + 20x + 75, one might re-write it as

x² + 15x + 5x + 75

Then, group the first two terms together, and the last two terms together:

x² + 15x + 5x + 75

Now, remove a common factor of x from the first group, and a common factor of 5 from the second group:

x(x + 15) + 5(x + 15)

And remove the new common factor of (x + 15): (x + 15)(x + 5)

Since I'm only guessing that this is what the assignment intends, this may or may not be helpful. I'm SURE you can apply it to the first of your problems.....

 

[needmadhelp]

im sorry excuse what ive said about the degrees but you guys are right thats what i have to do, i just need the steps on doing so.

 

[needmadhelp]

i have to change the 3 terms to 4 terms and then do the x(x-4)x(x-4) <---- example ) thing.

 

[needmadhelp]

Mrspi the way you are doing it is what im supposed to be doing. i would like to get the answers to the questions, but that seems like too much to ask , so can you demonstrate how to do it?

 

[needmadhelp]

yeah i didnt know how to explain it until mrspi said that.

 

[needmadhelp]

is this correct ?

k^2-13k+40

(k^2-8k) - (5k-40)

K(k-8) 5(k-8)

if so , then by god thank you.


i also need some help with this ; 12x^3+9a^2-30a
ive simplified it but need help from there : 4x^3+3a^2-10a
dont know if im supposed to change the 3a^2 to 3a or not