The monotone increasing interval of function y = lg|x + 1 / x|is ditto

The monotone increasing interval of function y = lg|x + 1 / x|is ditto

(- infinity, - 1) minus
(- 1,0) increase
(0,1) minus
(1, infinite) increase

Find the monotone increasing interval of function y = LG (4-x2)______ ．

Let t = 4-x2, t be a quadratic function with respect to x, and its image is a parabola with opening downward. With respect to Y-axis symmetry, t increases with the increase of X in the interval (- 2,0), and t increases with the increase of X in the interval (0,2)

It is proved that f (x) = LG (x + √ x square + 1) is an odd function

First confirm that the domain is r
then,
-f(x) = -lg[x+√(x^2+1)] = lg[1/(x+√(x^2+1))],
After the denominator is rationalized, the above formula = LG [√ (x ^ 2 + 1) - x] = f (- x)

High school mathematics: S = {1,2,3,4,5,6,7,8}, how many pairs of sets composed of two elements of S, how to calculate

Here, two are specified, that is, to select two of the eight elements, how many of them are selected. Using the algorithm of combination number (I don't know if you have learned it), the formula is 8 * 7 / 2 * 1 = 28