Crazy Comparing

Algebra Level 4

Let \[A=\bigg[\frac{(x+1)(x+2)}{2}\bigg]^2-\bigg[\frac{x(x+1)}{2}\bigg]^2\] \[B=(x-1)(\frac{3x}{2}-1)+\frac{\displaystyle \sum_{i=1}^{x-2} i^2-(x-2)(\frac{x-1}{2})}{2}+x(x+2)\] Here, \(x\) is a positive integer. Which is bigger, \(A\) or \(2B\)?