Given the function f (x) = LG1 − X1 + X, if f (a) = 12, then f (- a)=______ ．

Given the function f (x) = LG1 − X1 + X, if f (a) = 12, then f (- a)=______ ．

∵ 1 − X1 + X ＞ 0, ∵ 1 ＜ x ＜ 1; f (- x) + F (x) = LG1 − X1 + X + LG1 + x1 − x = LG1 = 0, ∵ f (- x) = - f (x), that is, the function f (x) = LG1 − X1 + X is odd; ∵ f (a) = 12, ∵ f (- a) = − 12

Given the function f (x) = LG [(a ^ 2-1) x ^ 2 + (a + 1) x + 1], if the value range of F (x) is r, find the value range of real number a
Although many similar solutions can be found, I think that solution is wrong. The required value field is r, not the definition field. I hope you can give me the answer!

If the value range is r, all positive numbers will be obtained
So the minimum value of true number is less than or equal to 0
Because if the minimum is greater than 0, the positive number between 0 and the minimum cannot be obtained
So the range is not R
a=1
Then the true number is 2x + 1 and all positive numbers can be obtained
a=-1
True number = 1, can't get all positive numbers
a≠±1
Quadratic function takes all positive numbers
The opening is upward
a²-1>0,
a1
The minimum value is less than or equal to 0, that is, it has a common point with the X axis
So the discriminant is greater than or equal to 0
a²+2a+1-4a²+4>=0
3a²-2a-5

Given the function f (x) = | LG (x-1) |, if a ≠ B and f (a) = f (b), then the value range of a + 2b is______ ．

First, draw the graph of the function f (x) = | LG (x-1) |, as follows: ∵ a ≠ B, and f (a) = f (b), ∵ LG (A-1) = LG (B-1), that is, 1A − 1 = B-1, ∵ B = 1 + 1A − 1, let B < A, then 1 < B < 2, ∵ a + 2B = a + 2 × (1 + 1a − 1) = (A-1) + 2A − 1 + 3 ≥ 3 + 22, ∵ when a = 1 + 2

The function f (x) = | lgx |. If a ≠ B and f (a) = f (b), then the value range of a + B is ()
A. （1，+∞）B. [1，+∞）C. （2，+∞）D. [2，+∞）

(method 1) because f (a) = f (b), so | LGA | = | LGB |, let 0 | a | B, then 0 | a | 1 | B, | LGA = - LGB, LGA + LGB = 0 | LG (AB) = 0 | AB = 1, a | 0, B |, and a ≠ B | (a + b) 2 | 4AB = 4 | a + B | > 2, so select C. (method 2) from the definition domain of logarithm, let 0 | a | B, and f (a) = f (b), get: 0 | a | 11 | bab = 1 The expression is: 0 ＜ x ＜ 11 ＜ YXY = 1, so the problem is transformed into the problem of finding the value range of Z = x + y, then z = x + y {y = - x + Z, that is, finding the maximum intercept of the function. According to the definition of derivative, when y = 1x {y ′ = − 1x2 ＜− 1} function image passes through point (1,1), Z has the minimum value of 2 (because it is an open region, so it can't be taken as 2), and the value range of a + B is (2, + ∞)

How to calculate 7x10 out of 11 + 7out of 11 with a simple algorithm?

7/11 *10 +7/11=7/11 *(10+1)=7

How many degrees centigrade times how many seconds is one joule

At least I can only write the following style:
1J = 1 Nm = 1 kg.m/s^2 .m = 1 kg.m^2/s^2
. means to multiply
All the above are standard international units. They are converted into basic units

(3/8+1/3—0.75)×24

We get 3 / 8x24 + 1 / 3x24-3 / 4x24, 3x3 + 1x8-3x6, 9 + 8-18 and-1

The ammeter with a range of 1A has a resistance of 0.1 ohm. It should be changed into 6A

The voltage at both ends of shunt resistor R in parallel is u = IO * r = 1A * 0.1 Ω = 0.1V
The over-r current is I = 6a-1a = 5A
R = u / I = 0.1/5 = 0.02 Ω
Shunt resistance of 0.02 ohm in parallel

Second grade mathematics is an applied problem
Fengshou No.1 wheat experimental field is a square with a side length of a meter minus a square reservoir with a side length of 1 meter. Fengshou No.2 wheat experimental field is a square with a side length of (A-1) meter, and the wheat harvested in both experimental fields is m kg
(1) What kind of wheat has high yield per unit area?
(2) How many times is the mass per unit area higher than that of the mass per unit area lower?

(1) No.1 area = A & # 178; - 1; No.2 area = (A-1) &# 178;;  A & # 178; - 1 - (A-1) &# 178; = A & # 178; - 1-A & # 178; - 1 + 2A = 2a-2;  a  2a-2 > 0;  No.1 area is large;  Fengshou No.2 has high yield (2) high quality per unit area  low quality per unit area = m / (A-1) &# 178;  M

When the secondary coil U2 of step-up transformer increases, how does the primary coil U3 of step-up transformer change? Why

Increase
With the increase of U2, the voltage to wire resistance and U3 increases