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**Kandai****Guest**

I know how to get from here:

-2(w-5)(w+5)(w^2+25)

to here:

-2w^4+1250

But I don't know how to get from here:

-2w^4+1250

to here:

-2(w-5)(w+5)(w^2+25)

The same with this problem:

a^9-1

(a-1)(a^2+a+1)(a^6+a^3+1)

**ganesh****Moderator**- Registered: 2005-06-28
- Posts: 17,274

Its always difficult to find the factors, given the simplest form.

a^3 - b^3 is (a-b)(a^2 + ab + b^2).

If one of the factors is known, it becomes a bit easier.

For lower degrees, by remembering some formulae, it can be done easily.

Like a^2 - b^2 = (a+b) x (a-b),

(a^3 + b^3) = (a+b) x (a^2 - ab + b^2) etc.

When you are aksed to prove that the LHS is equal to the RHS,

it is always better to start with lower degrees.

Character is who you are when no one is looking.

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