The monotonicity of function f (x) = x2-2ax + 3 in (- 2,2) is discussed

The monotonicity of function f (x) = x2-2ax + 3 in (- 2,2) is discussed

The axis of symmetry equation of the function f (x) = x2-2ax + 3 is: x = a, when a ≤ - 2, the function f (x) = x2-2ax + 3 monotonically increases in the interval (- 2, 2); when - 2 < a < 2, the function f (x) = x2-2ax + 3 monotonically decreases in the interval (- 2, a) and monotonically increases in the interval [a, 2]; when a ≥ 2, the function f (x) = x2-2ax + 3 monotonically decreases in the interval (- 2, 2)

We know whether the function [y = the negative quadratic of x] is an increasing function or a decreasing function on (0, + 00) and (- 00,0)

Function y = x ^ (- 2) = 1 / X & # 178;
When x ∈ (- ∞, 0), let x1

A truck and a motorcycle leave from a and B at the same time. The two vehicles meet for the first time at a distance of 60 km from a on the way. Then the two vehicles continue to move forward. When the truck arrives at B and the motorcycle arrives at a, they both return immediately. The two vehicles meet for the second time at a distance of 30 km from B on the way. What is the distance between a and B?

The total distance taken by two cars when they meet twice is three times that of a and B. suppose the total distance is x, then the equation is: (x + 30) + (X-60) × 3 = 3x4x-150 = 3x, x = 150; a: the distance between a and B is 150 km

Addition and subtraction of rational numbers in junior high school
- (1,4) + (5,6) + (2,3) - (1,2) (I use brackets for fractions)
Er, this. Of course, I can't do all of them, but I got stuck in one step
﹣（1,4）﹢（5,6）﹢（2,3）﹣（1,2）
=﹣（1,4）﹣（1,2）﹢（5,6）﹢（2,3）
=﹣（1,4）﹣（2,4）﹢（5,6）﹢（4,6）
=﹣（3,4）﹢（9,6）
Then. I just want to ask how to change the following two scores!

=-3/4+3/2
=-3/4+6/4
=3/4

The two trains, a and B, left 560 kilometers apart at the same time and did not meet each other after 4 hours. The distance is still 20 kilometers. It is known that the train a runs 65 kilometers per hour and the train B runs every hour
How many kilometers per hour

B's speed is (560-4 × 65-20) △ 4 = 280 △ 4 = 70 (km) per hour
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The average of 12,8,10,7,9 is () and the median is ()

The average of 12,8,10,7,9 is (9.2) and the median is (9)
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On the AB section of the road, a rides a bicycle from a to B, and B rides a motorcycle from B to A. they start at the same time. After 80 minutes, they meet. B turns back immediately after arriving at a, catches up with a 40 minutes after the first meeting, and B returns immediately after arriving at B. how much time will it take for a and B to meet again?

80 × 3-80-40 = 240-80-40 = 120 minutes. A: A and B will meet again in 120 minutes

Given that x is the fractional part of the root sign 2, find the square of the root sign x + 1 / 2 of the square of X - 2

x=√2-1
So the original form
=（x-1/x）^2
=［（√2-1）-1/（√2-1）］^2
=［（√2-1）-（√2+1）］^2
=（-2）^2
=4

The distance between the two places is 84 kilometers. A and B run from the two places at the same time. They meet in four fifths of an hour. A runs 54 kilometers per hour on average, and B runs how many kilometers per hour on average?

Vehicle B speed = 84 △ 4 / 5-54 = 51

In trapezoidal ABCD, ad is parallel to BC, e f is the midpoint angle B of ad BC plus angle c equal to 90 degrees, and EF = 1 / 2 (BC) is proved

It is proved that if the intersection of Ba and CD is extended at o point respectively, then ∠ BOC = 90 ° and ﹥ AOD and ﹥ BOC are all right angles ﹥ OE = EA = ed, of = FB = FC, ﹥ OE = & frac12; ad, of = & frac12; BC, ﹥ ef = & frac12; (BC-AD)