Three inequalities are known: ① AB > 0. ② BC ad > 0. ③ C / a > D / b. taking two of them as conditions and the remaining one as conclusion, the number of correct propositions that can be formed is

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• 1. If a > b, C
• 2. If A-B = 1 + √ 3, B-C = 1 - √ 3, find the value of 1 / (A & # 178; + B & # 178; + C & # 178; - AB AC BC)
• 3. If point C is the golden section of line AB, and AC
• 4. The position of the known real number AB on the number axis is shown in the figure: try to simplify: root (a-b) &# 178; - | a + B|
• 5. The positions of real numbers a and B on the number axis are shown in the figure. Try to simplify | a + B | + | A-B | + | ab| -----b--------0--------a--------》
• 6. The positions of real numbers a and B on the number axis are shown in the figure ────┴──┴─────┴─────┴─┴──＞ b -1 0 a 1 A.a+b>0 B.ab>0 C.a-b>0 D.|a|>|b|
• 7. If two points a and B on the number axis represent real numbers a and B respectively, the length of line AB is () A. a-bB. a+bC. |a-b|D. |a+b|
• 8. An inequality is a formula that uses (), (), or () to represent the size relationship
• 9. Inequality is the expression of () relation
• 10. Inequalities are formulas that use symbols (), (), (), () to denote inequality relations The answers at the midpoint are greater than, less than, greater than or equal to, less than or equal to and not equal to But there are only the first four items in the book, which is not equal to the answer Please give me some advice But there is no sign "not equal" in the textbook, only greater than, less than, greater than or equal to, less than or equal to It is said in the textbook that, in general, formulas connected by the symbols "< (or" less than or equal to "), and" greater than "(or" ≥) are called inequalities. There is no ≠ sign
• 11. In △ ABC, point D is the intersection of bisector of ∠ C and base ab. the following inequality is proved: CD & # 178; = AC · BC-AD · BD
• 12. What's the difference between the solution of inequality and the existence of inequality? For example, is x greater than 1-B / a the same as x greater than 1-B / a? Good and quick answer,
• 13. On the existence of inequalities For any real number x, the inequality │ x + 1 │ + X-2 │ > a holds, and the value range of real number a is obtained Analysis 2: using the absolute value inequality │ a │ - B │ ＜ a ± B │ ＜ a │ + B │ to solve the minimum value of F (x) = │ x + 1 │ + X-2 │ Let f (x) = x + 1 + X-2, x + 1 + X-2 = 3, f (x) min = 3. A < 3 Why can we do this?
• 14. Given C > 0, let P: function y = C ^ X be a decreasing function on R; Q: inequality x + | x-2c | >
• 15. It is proved that for any a, B, C, D ∈ R, there is an inequality (AC + BD) ≤ (a + b) (c + D),
• 16. It is proved that for any ABCD, there is always (AC + BD) & sup2; ≤ (A & sup2; + B & sup2;) (C & sup2; + D & sup2;)
• 17. Prove the inequality: (A & sup2; + B & sup2;) (C & sup2; + D & sup2;) ≥ (AC + BD) & sup2;
• 18. It is proved that for any a, B, C and D, they belong to R, and there is an inequality (AC + BD) ^ 2
• 19. The proof of inequality (AC + BD) & sup2; ≤ (A & sup2; + B & sup2;) (C & sup2; + D & sup2;)
• 20. There are four inequalities: (1) A2 + B2 + C2 ≥ AB + BC + AC; (2) a (1-A) ≤ 14; (3) BA + ab ≥ 2; (4) (A2 + B2) (C2 + D2) ≥ (AC + BD) 2; where () A. 1 B. 2 C. 3 d. 4