1.The final formula for the moment of inertia about the origin is the double integral of a region of r squared density dA.
关于原点的转动惯量，就是在区域上，求r^2*δ*dA的二重积分。
2.It is usually best to avoid substitution of numerical values until the final formula has been obtained.
在得到最终公式以前最好不要代入数值。
3.This is the final formula to be entered in cell B1
下面是要输入单元格B1中的最终公式