I understand most of Algebra except factoring. I don't understand how "canceling out" really works. Can someone please explain?

- stapel_eliz
**Posts:**1628**Joined:**Mon Dec 08, 2008 4:22 pm-
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What do you mean by "canceling out" in factorization? (I'm familiar with cancelling factors to simplify fractions, but that's a separate process from the factorization, and is in a different context.)I understand most of Algebra except factoring. I don't understand how "canceling out" really works. Can someone please explain?

Providing an example from your text or your class notes would be helpful. Thank you!

Here is one of my problems that I am struggling with:

FACTOR x to the 4th power - 9y squared

Then is says "1. x to the 4th power = (x squared) squared, and 9y squared = (3y) squared." I understand that.

And then it says "2. x to the 4th power - 9y squared = (x squared) squared - (3y) squared." I understand that, too, because I just said those were equal.

THEN, suddenly, it says it says, "3. And so, x to the 4th power - 9y squared = (x squared + 3y)(x squared - 3y). Solved"

WHERE did that come from??? Can someone please explain why (x squared) squared - (3y) squared turns into (x squared + 3y)(x squared - 3y)???

FACTOR x to the 4th power - 9y squared

Then is says "1. x to the 4th power = (x squared) squared, and 9y squared = (3y) squared." I understand that.

And then it says "2. x to the 4th power - 9y squared = (x squared) squared - (3y) squared." I understand that, too, because I just said those were equal.

THEN, suddenly, it says it says, "3. And so, x to the 4th power - 9y squared = (x squared + 3y)(x squared - 3y). Solved"

WHERE did that come from??? Can someone please explain why (x squared) squared - (3y) squared turns into (x squared + 3y)(x squared - 3y)???

- stapel_eliz
**Posts:**1628**Joined:**Mon Dec 08, 2008 4:22 pm-
**Contact:**

From factoringTHEN, suddenly, it says it says, "3. And so, x to the 4th power - 9y squared = (x squared + 3y)(x squared - 3y). Solved"

WHERE did that come from???

They applied the formula that should have been covered in class; check that section, or a section or two previous, to find the formula in your book.

Thanks, stapel_eliz. I looked at that formula, and I think I understand it. I geuss I just skipped it by accident in my book. Thank you!