# Thread: Expand and simplify 1-(AB - C)^2

1. ## Expand and simplify 1-(AB - C)^2

Hi can anybody help me solve this problem. I just cant see how it works

1-(AB - C)^2 = 1 - A^2 -B^2 - C^2 + 2ABC

2. Hi,

are you sure it's not $\displaystyle 1-(ab-c)^2 = 1-(ab)^2-c^2+2abc$?

3. No I'm positive its

1-(AB - C)^2 = 1 - A^2 -B^2 - C^2 + 2ABC

Thats why I'm really confused

4. Then I'm confused as well.

5. Originally Posted by Turloughmack
No I'm positive its

1-(AB - C)^2 = 1 - A^2 -B^2 - C^2 + 2ABC

Thats why I'm really confused
Obviously there is a typo in the Right Hand Side. The minus between the A^2 and B^2 should not be there.