Seventh grade math homework is badly needed! ! ! Go, go, go, go. ! !

The distance from 1.3 to the origin is 3; The distance from -5 to the origin is 5.

2. Simplify:

|+2|=2,| 1/5|= 1/5,|0|=0,|-3|=3,|-0.2|=0.2,

|-8.2|=8.2,|-2.6|=2.6,-|+3|=-3,-|-8|=-8。

Generally speaking, the distance between the point representing the number A on the number axis and the origin is called the absolute value of the number A, and it is recorded as |a|.

4. Compare by law: positive number >; 0，0 & gt； Negative number, positive number > negative number, two negative numbers, the larger absolute value is smaller.

The absolute value of 5. -2 is 2; The reciprocal of |-7| is-7; Numbers whose absolute value is equal to 4 are 4 and -4.

6. Numbers whose absolute values are equal to themselves are 0 and positive numbers.

7. There are five integers whose absolute value is less than 3, namely -2,-1, 0, 1, 2, and the smallest is -2.

8. Judgment: (1) Negative numbers have no absolute value. (2) The rational number with the smallest absolute value is 0. (3) The absolute value of any number is non-negative. (4) The absolute values of two opposite numbers are equal. Among them, (b) is correct.

1。

9. If |x|=|-2.5|, then x=-2.5 or 2.5.

10. Calculation:

①(+8)+(+5)= 13 ②(-8)+(-5)=- 13

③(+8)+(-5)=3 ④(-8)+(+5)=-3

⑤(-8)+(+8)=0 ⑥(+8)+0=-8

⑦5+(-22)=- 17 ⑧(- 1.3)+(-8)=-9.3

⑨(-0.9)+ 1.5=0.6 ⑩2.7+(-3.5)=-0.8

( 1)(+2 1)+(-3 1)=- 10

(2)(-3. 125)+(+3 8 1) =-0. 125+ 1/8 =-0. 125+0. 125 = 0.

(3)(-3 1)+(+2 1) =- 1/3+ 1/2 =-2/6+3/6 = 1/6.

(4)(-3 1/3 1)+0.3 =- 10/3+ 10 =- 100/30+9/30 =-9 1/30.