((r-1)^2)(r+1)

How do I expand this? Thanks,

JN

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- May 27th 2008, 11:38 AMJim NewtExpand this
((r-1)^2)(r+1)

How do I expand this? Thanks,

JN - May 27th 2008, 11:42 AMearboth
- May 27th 2008, 11:43 AMMoo
Hello,

You can do this in two ways :

- develop by using the identity : (a-b)²=a²-2ab+b², then multiply by (r+1). But this will make a multiplication 3 terms by 2 terms

- write :

Use the identity : (a-b)(a+b)=a²-b²

Then, it will be a multiplication 2 terms by 2 terms, which is more beautiful (Evilgrin)