Factorisation

[Juri]

I tried to solve

x^2-y^2-4y-4 and got an answer of (x-y-2) (x+y+2).

I was wondering if I got it right.

 

[Juri]

I followed the order of:

1. x^2 - (y^2 - 4y - 4)
2. X^2 - (y + 2)^2
3. x - (y + 2) • x + (y + 2)
4. (x - y - 2) • (x + y + 2)

 

[lev888]

I followed the order of:

1. x^2 - (y^2 - 4y - 4)
2. X^2 - (y + 2)^2
3. x - (y + 2) • x + (y + 2)
4. (x - y - 2) • (x + y + 2)

How do you check whether factorization is correct?

 

[Juri]

The answer is usually correct when the answer is simplified but is still equal to the original expression when you multiply it out again.

 

[lookagain]

I followed the order of:

1. x^2 - (y^2 - 4y - 4) . . . . . The signs inside are not correct.
2. X^2 - (y + 2)^2 . . . . . . . . That leading letter needs to be in lower case.
3. x - (y + 2) • x + (y + 2) . . . . . Grouping symbols are missing.
4. (x - y - 2) • (x + y + 2) . . . . . You can drop the multiplication dot for style purposes.

Look at this:

1. x^2 - (y^2 + 4y + 4)
2. x^2 - (y + 2)^2
3. [x - (y + 2)][x + (y + 2)]
4. (x - y - 2)(x + y + 2)

 

[Juri]

Look at this:

1. x^2 - (y^2 + 4y + 4)
2. x^2 - (y + 2)^2
3. [x - (y + 2)][x + (y + 2)]
4. (x - y - 2)(x + y + 2)

Thanks for pointing out the little error!

I’m glad (x- y - 2) (x + y + 2) is the answer.