If you do something, the success rate is one-third, what is the probability of doing it three times and all three times

If you do something, the success rate is one-third, what is the probability of doing it three times and all three times

Or one third, the success rate does not change with the number of practice

Why don't things with probability equal to 1 be inevitable

Common sense: the length, area and volume of a single point are all zero. 2. If the area where a random event is located is a single point, because the length, area and volume of a single point are all zero, the probability of its occurrence is zero, but it is not an impossible event

When k is what number, the solution of equation 5x-6 = 3 (x + y) is (1) positive; (2) negative; (3) greater than k

（1）5x-6=3x+3k
2x=3k+6
x=(3k+6)/2>0
3k+6>0
k>-2
(2)Kk
2k>-6
k>-3

How to find the monotone decreasing interval of function y = 1 / 3x & # 179; - 1 / 2 (a + A & # 178;) x & # 178; + A & # 179; X + A & # 178;)!

Derivation, re derivation

In the original algorithm of rational number, we add the new operation "*" as follows: when a ≥ B, a ∧ B = B & # 178; when a < B, a ∧ B
Find the value of (1 ⁃ x) × X - (3 ⁃ x) when x = 2

Your question is not perfect, mainly in the last "when a < B, a * B". Now suppose "when a < B, a * b = a", refer to the original question for the specific situation. Only provide the solution. When x = 2, the original question can be changed into (1 * 2) × 2 - (3 * 2); for 1 * 2, let a = 1, B = 2, according to the known conditions, because 1 < 2, the

Given that the coordinates of point P about X-axis symmetry are (3-2a, 2a-5) and are the whole points in the third quadrant (the points whose abscissa and ordinate are all integers), then the point P coordinate is?

3-2a0
Solution
a=2
p(-1,-1)

The minimum positive period of the function f (x) = | SiNx + cosx | is a detailed process

The minimum positive period of F (x) = | SiNx + cosx | = | radical 2Sin (x + π / 4) | y = radical 2Sin (x + π / 4) t = 2 π
The minimum positive period of F (x) = | SiNx + cosx | = | radical 2Sin (x + π / 4) | t = π

Using the definition to prove that the function f (x) = - 2x ^ 2 + 4x + 3 is a decreasing function on (1, + ∞), how to find it?

Let x1, X2 > 1 and x1f (x2)
-2x1^2+4x1+3>-2x2^2+4x2+3
x2^2-x1^2>2(x2-x1)
(x2-x1)(x2+x1)>2(x2-x1) (x2-x1>0)
x2+x1>2 (x1>1,x2>1 ,x1+x2>2)
So f (x1) > F (x2) holds, so f (x) is a decreasing function

The intercept of the line 2x-3y = 6 on the Y axis is?

Let x = 0 and y = 2

1 / 2 + 5 / 6 + 11 / 12 + 19 / 20 +... 9701 / 9702 + 9899 / 9900

General term = (n (n + 1) - 1) / N (n + 1) = 1-1 / N (n + 1) = 1 - (1 / n-1 / (n + 1))
one