As soon as you see the absolute value, you should think about whether you can remove the absolute value to simplify the calculation. Then you need to see whether the number in the absolute value is positive or negative. When an >；; When 0, n < 5.5, the number of items in the series is an integer, so n is regarded as < 6. When n >, an < 0；; =6. Therefore

s 10 = a 1+a2+a3+a4+a5-(a6+a7+A8+a9+a 10)= 1 1 * 5-2 *( 1+2+)

Remember to try to get rid of it as soon as you see the absolute value, whether it is equality or inequality.