So supermarket b is the cheapest.
2. It can be concluded that the common divisor of the sequence is: (n squared +(- 1) N+ 1 power), and the seventh number is 1/50.
3. The last item should be one in 2005*2007, right? Otherwise, you can't ask for it.
From the last item, we can decompose 2005 * 2007 =1/2 * (2005-2007).
So1* 31+3 * 5+5 * 7+...+2005 * 2007.
= 1/2*( 1- 1/3+ 1/3- 1/5+ 1/5- 1/7.。 . . . . 1/2005- 1/2007)
= 1/2*( 1- 1/2007)
= 1003/2007
4 can be solved by three problems:
= 1/3*( 1- 1/2008)
=669/2008
5. The absolute value of a-4 +2-a =4-a+a-2=2.
6. Equal to 2
You can set the three numbers of abc as 1, 1, 1, or-1,-1.
7.A
8.B
9.6650 * 7.6%-4780 * 3.87%-1* 4.8-128 =139438+0.4 million yuan.