Given the function f (x) = x + m / x, and the function image passes through the point (1,5), judge the monotonicity of function f (x) on [2, + ∞), and prove your conclusion with the definition

Given the function f (x) = x + m / x, and the function image passes through the point (1,5), judge the monotonicity of function f (x) on [2, + ∞), and prove your conclusion with the definition


Let f (x) in (1,5) generation f (x), 1 + M = 5, M = 4, so f (x) = x + 4 / X definition, any x1, X2 belong to [2, + ∞], and X10 △ y = f (x2) - f (x1) = x2 + 4 / x2-x1-4 / X1 = x2-x1 + 4 (x1-x2) / x1x2 = (x2-x1) (x1x2-4) / x1x2-x1 > 0, x1x2 > 0, x1x2-4 > 0, so △ Y > 0, that is, the function f (x) is in [2, + ∞)



The function f (x) = x + m / X is known, and the function image passes through points (1,5). The monotonicity of function f (x) on [2, + ∞) is discussed and proved by definition. It is better to write down the draft paper and send pictures





F (x) = 2x / x ^ 2 + 1 of the parity, monotonicity, draw the function image, find the function maximum


F (- x) = - 2x / (x ^ 2 + 1) = - f (x) is an odd function F & # 39; = & nbsp; (2 (x ^ 2 + 1) - 2x (2x)) / (x ^ 2 + 1) ^ 2 & nbsp; = & nbsp; 2 (1-x ^ 2) / (x ^ 2 + 1) ^ 2 & nbsp; = 2 (1-x) (1 + x) / (x ^ 2 + 1) ^ 2, so [- 1,1] monotone increasing (- infinity, - 1) & nbsp; (1, + infinity) monotone decreasing maximum f (1) = 1 minimum f (- 1) = - 1



Let a be a matrix of order 3, A1 and A2 be the eigenvectors of a belonging to eigenvalue-1 and 1 respectively, and A3 satisfy the condition that aa3 = A2 + a3. It is proved that A1, A2 and A3 are linearly independent


It is proved that let k1a1 + k2a2 + k3a3 = 0 (1)
Then k1aa1 + k2aa2 + k3aa3 = 0
It is known that - k1a1 + k2a2 + K3 (A2 + a3) = 0
That is - k1a1 + (K2 + K3) A2 + k3a3 = 0 (2)
(1)-(2):2k1a1-k3a2 = 0
Because A1 and A2 are the eigenvectors of a which belong to the eigenvalues - 1 and 1 respectively,
So A1 and A2 are linearly independent
So K1 = K3 = 0
Substituting (1) to know K2 = 0
So A1, A2, A3 are linearly independent



What is the solution of X Λ 2-7x + 9 = 0?


a=1,b=-7,c=9,
△=b^2-4ac=49-36=13,
x=(7±√13)/2



Let two independent random variables X and y have the same distribution rate, and the distribution rate of X is x 0 1 P & nbsp; 12 & nbsp; 12, then the distribution rate of random variable z = max {x, y} is x 0 1 P & nbsp; 12______ .


The combination of solutions (x, y) has the following four cases: (0,0), (0,1), (1,0), (1,1) the corresponding probabilities are 14. For the latter three cases, z = 1, for the first case, z = 0. Therefore, the distribution law of Z is Z = 0, P = 14, z = 1, P = 34



If x + MX-15 = (x + 3) (x + n), what is the value of M


x²+mx-15=x²+(n+3)x+3n
∴m=n+3
-15=3n
∴m=-2
n=-5



In the isosceles trapezoid ABCD, AD / / BC, angle B = 45 degrees, AE vertical, BC and point E, AE = ad = 2, then the trapezoid median line is


The triangle Abe is an isosceles right triangle trapezoid, the upper bottom is 2, and the lower bottom is composed of three parts. The corresponding part of AE's upper bottom and the lower bottom corresponding to AE's right side are 2 + 2 + 2 equal to 6, so the median line is 2 + 6 divided by 2 equal to 4



If the power of 2n + 1 + 3 of 3 is 324, try to find the value of n
3 ^ (2n + 1) + 3 ^ (2n) = 324 3 * 3 ^ (2n) + 3 ^ (2n) = 324 4 * 3 ^ (2n) = 324 3 ^ (2n) = 81 3 ^ (2n) = 3 ^ 4 2n = 4 N = 2 how does the power of 4 * 3 in the third step become 2n


Taking 3 ^ (2n) as a whole, a is 3A + a = 324, that is 4A = 324 * 3 ^ (2n) = 324



Sum Sn = 1 + 11 + 111 + +11…… 11 (n 1)


In this way, you want SN to be the first n terms of sequence an and a (n) = a (n-1) + 10 ^ (- n) a (2) = a (1) + 10 ^ (- 2) a (3) = a (2) + 10 ^ (- 3) a (4) = a (3) + 10 ^ (- 4)