# Thread: Factorize x^5-16x- how do u do questions like this?

1. ## Factorize x^5-16x- how do u do questions like this?

Hi, I wanted to ask how to do questions like the one that I put in the title,\-

Factorize x^5-16x- how do u do questions like this?

would you o, in the first step, separate the equation into x^2.5 power,? no, right? I'm not sure- that's the only way that i can see right now,... can u help?

~shapoey

2. Originally Posted by shapoey
Hi, I wanted to ask how to do questions like the one that I put in the title,\- would you o, in the first step, separate the equation into x^2.5 power,? no, right? I'm not sure- that's the only way that i can see right now,... can u help?

~shapoey
x^5 - 16x ....................... Is there a common factor ← yes → factor that out.

= x * (x^4 - 16)

= x * (x^4 - 2^4)

What is special about the expression within the parentheses?

3. Originally Posted by shapoey
Hi, I wanted to ask how to do questions like the one that I put in the title,\-

Factorize x^5-16x- how do u do questions like this?
To learn how to do simple factorization, try here. This will explain the first step in the response you received earlier.

To learn how to do special factorization (of the difference-of-squares type suggested in the previous response), try here.

To learn how to factor quadratics (a topic which usually occurs between the two topics above), try here.

Originally Posted by shapoey
would you o, in the first step, separate the equation into x^2.5 power,?
I'm sorry, but I don't know what this means...? How are you getting a power of 5/2? Where are the radicals coming from? How did you go from "x^5 - 16x" to... whatever it was that you got? What did you get?

Originally Posted by shapoey
Also, do u know about the cross method for factorization? I don't get how that works either.
Please provide an example what this "cross method". Thank you!

4. Originally Posted by stapel
Please provide an example what this "cross method". Thank you!
I shall bet you my next martini that what is meant is the difference of squares.

And of course you can use difference of squares in this problem.

5. Originally Posted by JeffM
I shall bet you my next martini that what is meant is the difference of squares.

And of course you can use difference of squares in this problem.
After doing the initial simple factorization, yes!

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