Gold medal mathematics has been passed four times in each course.

1, remove the sign of absolute value, and the original formula is =156/1/5+156/157-1/2 =

2. Original formula = (1-1/2) (1+1/2) (1-1/3) (1+/kloc-)

= 1/2*3/2*2/3*4/3*3/4*5/4......2007/2008*2009/2008*2008/2009*20 10/2009

= 1/2*20 10/2009= 1005/2009

3. Original formula =- 1*50=-50

I don't understand this topic.

5.2x3 = 2 * 3+2-3 = 5,1x (-4) =-4+1-(-4) =1,so the original formula =5+ 1=6.

6. Original formula =1/2 * (1/3-1/5+1/7+1/9+) ...