(1) First of all, it is found that the number is the n power of 3, the odd position of the symbol is negative, and the even position is positive, so the general term can be found;

(2) It is easy to find that the numbers corresponding to the second row number and the first row number are +2, and the numbers corresponding to the third row number and the first row number are multiplied by1/3;

(3) Find the number 10 corresponding to three lines from the general term obtained in (1)(2), and calculate the sum of these three numbers to get the answer.

Answer:

Solution:

( 1)-3=(- 1)^ 1x3^ 1，

9=(- 1)^2x3^2，

-27=(- 1)^3x3^3，

8 1=(- 1)^4x3^4，

…

So the nth term is (-1) nx3n;

(2) Add -2 to the numbers corresponding to the second line number and the first line number, and the nth item is (-1) nx3n-2; The numbers corresponding to the third line number and the first line number are multiplied by 1/3, and the nth item is (-1) nx3n-1;

(3) The number of 10 in the first line is (-1)10x310 = 310;

The number 10 in the second line is (-1)10x310-2 = 310-2;

The number 10 in the first line is (-1)10x310-1= 39;

The sum of these three numbers is 310+310-2+39 = 7× 39-2.