It is known that the quadratic function f (x) satisfies f (- 1) = 0, and 8x ≤ f (x) ≤ 4 (x ^ 2 + 1) holds constant for X ∈ R. the expression of (1) for f (1) and (2) for f (x) is obtained

It is known that the quadratic function f (x) satisfies f (- 1) = 0, and 8x ≤ f (x) ≤ 4 (x ^ 2 + 1) holds constant for X ∈ R. the expression of (1) for f (1) and (2) for f (x) is obtained

F (2) = f (4) 4 + 2B + C = 16 + 4B + C B = - 6, f (x) = x ^ 2-6x + C & gt; C-8 x ^ 2-6x + 8 & gt; 0 (X-2) (x-4) & gt; 0 X & gt; 4 or X & lt; 2, the axis of symmetry is x = - B / 2 = 3,

Let a, B, C, d be real numbers, if the absolute value of a + B = 4, the absolute value of C + D = 2, and the absolute value of a-C + B-D = C-A + D-B, find the maximum value of a + B + C + D

|a-c+b-d|=|(a+b)-(c+d)|
C-A + D-B = - (A-C + B-D)
That is, a-c + B-D is negative, that is to say, a + B

In the function y = x + radical x + 2 / X & # - 9, the value range of the independent variable?

y=x+√(x+2)/(x^2-9)
x+2>=0
x^2-9≠0
x> X = - 2 and X ≠ 3
X value range [- 2,3) ∪ (3, + ∝)