# Taking the square of a formula

1. Aug 30, 2016

### Pual Black

1. The problem statement, all variables and given/known data
Hi sorry if the titel is wrong

I want to know if i can write this

$a^2 + u^2 -2au= (a-u)^2 = (u-a)^2$
I get different results when integrating $x^{-\frac{3}{2}}$ in the range $(a-u)^2$ to $(a+u)^2$

2. Aug 30, 2016

### Staff: Mentor

Yes, these expressions are all equal.

3. Aug 30, 2016

### Pual Black

I've uploaded my work as images.
Sorry for not using LaTex but im on mobile phone.

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4. Aug 30, 2016

### Staff: Mentor

I think the problem might be from taking the square root of (a - u)2. It's not necessarily equal to a - u. What is true is that $\sqrt{(a - u)^2} = |a - u|$ which in turn is equal to $|u - a|$.

5. Aug 31, 2016

Ok i got it.