Judging from the meaning of the question: x+2y= 10

Deformation: y = 5-x 2 because 0≤x≤ 10, and both x and y are integers,

Therefore, the acceptable values of x are 0,2,4,6,8, 10.

Therefore, * * * has six alternatives.

2

. N and 1/(n? - 1)=n？ × 1/(n？ - 1)

3.

100+ 1)×2=202

(202+ 1)×2=406.

(406+ 1)×2=8 12.

Original 8 12 peach

4.

Solution: ∫1+2+3+…+2012 = (2012+1) × 2012 ÷ 2,

The sum of the single digits of these 20 12 natural numbers is 8.

Once again, all other numbers have been erased, leaving only 12 and another number.

∴ Another number is the single digit of the erased sum of three numbers, which must be less than the single digit of the sum of 10 and 12, so it is 6.

5. The distance between+1006 and negative1006 is exactly 20 12.

This sum is exactly 0, that is, for example, the distance from-1000 to-1006 is 6, and the distance from 1006 is 20 12.

∴ From-1006 to 1006, the corresponding number is exactly the sum of antonyms of 1006.

∴ Addition =0

6.① After removing the absolute value, it is 2x-6 = 4.

∴x？ =5，x？ = 1

② When x≥2, the absolute value is directly removed.

∴x-2+2x+ 1=8 ∴x=3

When-1/2 ≤ x < 2

Only the absolute value of |x-2| is removed and becomes the reciprocal.

∴2-x+2x+ 1=8 ∴x=5

When x

Remove the absolute value of the two and become the opposite number.

∴2-x -2x- 1=8 ∴x=-7/3

7. First of all, because the former is smaller than the latter.

Remove the absolute value and become the opposite number.

∴ 1- 1/2 ﹢ 1/﹣ 1/3﹢ 1/3- 1/4......﹣ 1/ 100= 1- 1/ 100=99/ 100

Second, the tomb is completely converted into 10000.

The numerator and denominator of the first formula are × 1000, the second formula is × 100 and the third formula is × 10.

Addition = 38889/ 10000

(3) The method is the same as above.

1- 1/ 10- 1/ 100- 1/ 1000-…- 1/ 10000000000

= 1-( 1/ 10+ 1/ 100+...+ 1/ 10000000000)

= 1- 1 1 1 1 1 1 1 1 1/ 10000000000)

=888888889/ 10000000000