For the function f (x) = 1 / X (x > 0) in the domain x1, X2 (x1 ≠ x2), we have the following conclusions 1.f（x1+x2)=f（x1）+f（x2）；2.f（x1x2）=f（x1）f（x2）；3.f(x1)-f(x2) / x1-x2; 4.f(x1+x2 / 2)＜f(x1)+f(x2) / 2 The correct conclusion in the above conclusion is -- () the answers are 2 and 4, but I don't know why 4 is right,

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• 1. Let y = log2 ^ (0, + ∞). If f (x) = lgx, try to judge 1 / 2 "f (x1) + F (x2) and 1 / 2" f (x1) + F (x2) according to the image of F (x) F "((x1) + (x2)) / 2"
• 2. It is known that the zeros of the function y = x ^ 2 + 2mx + 2m + 3 (M belongs to R) are x1, x2, Find the minimum value of X1 ^ 2 + x2 ^ 2
• 3. If M belongs to R X1 and X2 are two zeros of the square of the function f (x) = x-2mx + 1-m, then the minimum value of the square of X1 plus the square of X2 is——————
• 4. If the function f (x) = x ^ 2-3x-k has zeros on (- 1, 1), then the value range of K
• 5. If f (x) = x ^ 2-2 / 3x-k has zero on [- 1,1], then the value range of real number k I want a detailed process... Don't just give me an answer
• 6. If f (x) = x ^ 3 + ax ^ 2 + BX + 27 has a maximum at x = 1 and a minimum at x = 3, then a-b=
• 7. Given the function y = ax ^ 3 + BX ^ 2, when x = 1, there is a maximum of 3. Find (1) the analytic expression of the function and write his monotone interval (2) to find the maximum and minimum of the function on [- 2,1]
• 8. Given the real number a ≠ 0, the function f (x) = ax (X-2) ^ 2 (x belongs to R) (1). If the function f (x) has the maximum value 32 | 27, find the value of A (2) If the inequality f (x) < 32 holds for any x, the value range of a is obtained
• 9. It is known that the maximum value of function f (x) = ax ^ 3 + BX ^ 2 + CX at point x0 is - 4, and the image of derivative function y = f (x) passes through (1,0) (2,0) Find (1) x0 =? (2) find the value of a, B, C?
• 10. Given that the image of the function f (x) = AX3 + bx2 + CX + D (a ≠ 0) passes through the origin, f ′ (1) = 0, if f (x) reaches the maximum at x = - 1, 2. (1) find the analytic expression of the function y = f (x); (2) if f (x) ≥ f ′ (x) + 6x + m for any x ∈ [- 2,4], find the maximum of M
• 11. For any x1, X2 (x1 ≠ x2) in the domain of definition of function f (x), we have the following conclusion: (1) f (x1 + x2) = f (x1) * f (x2) (2) f (x1 * x2) = f (x1) + F (x) (1)f(x1+x2)=f(x1)*f(x2) (2)f(x1*x2)=f(x1)+f(x2) (3)[f(x1)-f(x2)]/(x1-x2)>0 (4) f[(x1+x2)/2]
• 12. For any x1, X2 (x1 ≠ x2) in the domain of function f (x), the following conclusions are obtained: (1) f (x1 + x2) = f (x1) + F (x2); (2)f(x1·x2)=f(x1)+f(x2); (3)[f(x1)-f(x2)]/(x1-x2)>0; (4)f[(x1+x2)/2]
• 13. For any x1, X2 (x1 ≠ x2) in the definition field of function f (x) = lgx, the following conclusion is obtained f(（x1+x2）/2)
• 14. X 2 ∈ (0. + ∞), if f (x) = lgx, compare the sizes of [f (x 1) + F (x 2)] / 2 and f [(x 1 + x 2) / 2]
• 15. The interval of zero point of function f (x) = lgx + X-5 is () A. （1，2）B. （2，3）C. （3，4）D. （4，5）
• 16. The interval where the zeros of the function f (x) = - (1 / x) + lgx lie is
• 17. The interval where the zeros of the function f (x) = - 1x + lgx are located is () A. （0，1）B. （1，2）C. （2，3）D. （3，10）
• 18. Try to find an interval of length one where the function y = (x-1) \ (3x + 2) has at least one zero point
• 19. The interval where the zeros of the function f (x) = 2x + 3x lie is______ ．
• 20. Find the zero point of function y = (3x ^ 2-x ^ 2) / (x ^ 2-1) + 1 / (1-x) - 2