The solution equation: 2.1 △ x = 0.3, 7.2-x = 4.3, x-0.84x = 0.8, 30 × (x △ 4) = 60, 84 + x = 10.2

Question 1 x = 7
Question 2 x = 2.9
Question 3 x = 5
Question 4 x = 8
Question 5 x = - 73.8

RELATED INFORMATIONS

1. Fill in the blanks: 1, 81, 64, 49, (), 25, (), () 2, 2, 3, 5, 8, (), (), 34
2. 1. Fill in the blanks according to the rules, （2）1,8,27,（）125,（） 2 (1) find the unknown X 5 / 3 x + 1 / 10 x = 7 / 5 5x-2.1 small X4 = 9.6 (4-1.6)x=36 2X divided by 5 = 15
3. The rules of 100, 81, 49, 36, (), 16, () are as follows
4. Find the rule 1,4,16,36,64100, ()
5. Find the rule: 2, - 4.6, - 8.10, 12.14, - 16, what are the 99th and 100th numbers? Explain why
6. Find the law of Mathematics (2,3), (10,6), (20,11), (9,)
7. Observe the following figures and their corresponding formulas. According to the rule you found, use n to represent 1 + 8 + 16 + 24 + +8N (n is a positive integer)______ ．
8. What is the result of 1 + 8 + 16 + 24 +. + 8N (n is a positive integer)?
9. Observe the following figures and their corresponding formulas. According to the rule you found, use n to represent 1 + 8 + 16 + 24 + +8N (n is a positive integer)______ ．
10. 1 + 8 = 3, 1 + 8 + 16 + 5, 1 + 8 + 16 + 24 = 7, 1 + 8 + 16 + 24 + ··········· + 8N (n is a positive integer)
11. 3: How to solve the equation? 30% × 2.5 + 3 / 10 × 3.7 + 0.3 × 3.7 is simple and convenient
12. (x+8)(x+6)(x+7)+(x+5)(x+6)(x+7)=(x+5)(x+8)(x+7)+(x+5)(x+8)(x+6)
13. X: 3.5 = 1.4:5.6, 1 / 2:1 / 5 = x: 1 / 10, 36 / x = 1.8:5, 2 / 5: x = 8 / 7:10, 3.6:0.9 = x: 0.15, X: 3 / 5 = 3 / 8:0.05 X: 3.5 = 1.4:5.6, 1 / 2:1 / 5 = x: 1 / 10, 36 / x = 1.8:5, 2 / 5: x = 8 / 7:10, 3.6:0.9 = x: 0.15, X: 3 / 5 = 3 / 8:0.05
14. 8 / x = 0.36 / 0.6
15. (5-x)*3=(7-x)*2 x*（1-0.2）=145-x+8 x*6+x（1+0.1）*5=1518 9+x =(36+x)*0.4
16. （-7/12-5/6+9/8-3/4）x（--36）
17. Given 1 + X + x ^ 2 + x ^ 3 = 0, find the value of X + x ^ 2 + x ^ 3 + x ^ 4 + x ^ 5 + x ^ 6 + x ^ 7 + x ^ 8 If not, how much?
18. (1) (- 1 / 12-1 / 36 + 3 / 4-1 / 6) * (- 48) (2) - 3 / 17 △ 3 * (17 / 5)) (3) - 5 ÷ (- 1 and 2 / 7) * 4 / 5 * (- 2 and 1 / 4) / 7 (4) - 2 of 13 * 3-0.34 * 2 of 7 + 1 of 3 * (- 13) - 5 of 7 * 0.34 (5) (- 1 / 6) / (2 / 3 1-3 / 3 2 + 1 / 15 4)
19. The sum of the two addends is 98. One addend increases by 7.36 and the other decreases by 5.5. What is the sum?
20. Simple calculation (- 98) * (- 0.125) + 98 * 1 / 8 * (- 4 / 7) (- 1 / 12-1 / 36 + 3 / 4-1 / 6) * (- 36) - 19 and 24 / 25 * (- 5)