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Mathematics 17 Online
OpenStudy (anonymous):

t^6-1= help pkease

OpenStudy (whpalmer4):

Trying to factor it?

OpenStudy (anonymous):

yes @whpalmer4

OpenStudy (whpalmer4):

Well, do recall that when we multiply polynomials, the final term always is just the product of the final terms in the polynomials? For example: \[(x+a)(x+b) = x^2+ ax + bx + ab\] That means our factors must have final terms that are factors of -1, right?

OpenStudy (whpalmer4):

Also, you should be looking at that and thinking "difference of squares!" because you can easily take the square root of both \(t^6\) and \(1)...

OpenStudy (whpalmer4):

sorry, \(t^6\) and \(1\)...

OpenStudy (whpalmer4):

So, two routes that we can go here (at least): 1) difference of squares 2) unraveling the factors by the rational root theorem Which do you want to do? Both is a perfectly acceptable response!

OpenStudy (anonymous):

difference of squares

OpenStudy (whpalmer4):

Okay, what squared gives us \(t^6\)?

OpenStudy (whpalmer4):

\[\sqrt{t^6} =\]

OpenStudy (anonymous):

t^3

OpenStudy (anonymous):

got it

OpenStudy (whpalmer4):

Right, so if we express \(t^6-1 = (t^3)^2-1\) as a product of two binomials, what are they?

OpenStudy (whpalmer4):

Now you can factor each of those again as a sum or difference of cubes...

OpenStudy (anonymous):

\[(t+1)(t ^2-t+1)(t-1)(t^2+t+1)\]

OpenStudy (whpalmer4):

You got it!

OpenStudy (anonymous):

thank you i got 3 more problems if u cxan help me

OpenStudy (whpalmer4):

by the RRT, we know that any factors must have +1 or -1, so we test them out to see if they give us 0: \[(1)^6-1 = 0\]\[(-1)^6-1=0\]So both of those are roots, which means we have factors of \((t-1)(t+1)\) which we can divide out and then hopefully recognize that we can factor the remaining part...

OpenStudy (whpalmer4):

let's see the first one

OpenStudy (anonymous):

c^2-4c+4

OpenStudy (anonymous):

wait wrong one t^2-24+144

OpenStudy (whpalmer4):

\[t^2-24t+144\]First quick check to make when factoring a trinomial like this: is it a perfect square? Take the coefficient of \(t\), divide by 2, square the result. If that equals the 3rd term, it's a perfect square.

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