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The distance between a and B is 360km. A car travels 160km from a to B in four hours. How many hours will it take to reach B?
The remaining distance divided by the speed equals the remaining time
(360-160) / (160 / 4) = 5 hours
How to calculate the average of 2x + 5,3y-3, x + y, 10
The average of 2x + 5,3y-3, x + y, 10 = (2x + 5 + 3y-3 + X + y + 10) / 4 = 3 / 4x + y + 3
The distance between a and B is 300 kilometers. It takes 20 hours for a to complete the whole journey, and it takes 30 hours for B to complete the whole journey. Now the two people are walking from a and B to each other at the same time, and they meet in a few hours
Time = 1 ÷ (1 / 20 + 1 / 30) = 1 △ 5 / 60 = 60 △ 5 = 12 hours;
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Let the definition field of function FX be (0, positive infinity) for any positive real number f (MN) = FM + FN, and if x > 1, FX > 0, F2 = 1, (1) find f (1 / 2)
(2) To prove that f (x) is an increasing function on (0, positive infinity)
(3) Finding the number of roots of the equation 4sinx = FX
(1) F (1) = f (1 × 1) = f (1) + F (1), so f (1) = 0
And f (1) = f [2 × (1 / 2)] = f (2) + F (1 / 2) = 0
So f (1 / 2) = - f (2) = - 1
(2) Set 00
Because f (x2) = f (x1 · (x2 / x1)] = f (x2) + F (x2 / x1)
So f (x2) - f (x1) = f (x2 / x1) > 0
F (x1)
On a map with a scale of 1:2000000, the distance between a and B is 7.5cm. On another map with a scale of 1:5000000
What is the distance between the two cities on the map?
Actual distance = distance on the map / scale = 7.5 * 2000000 = 15000000cm
Distance on the map = actual distance * scale = 15000000 / 5000000 = 3cm
Given that a, B and C are nonzero real numbers and satisfy B + Ca = a + BC = a + CB = k, then the image of the linear function y = KX + (1 + k) must pass ()
A. The first, second and third quadrants B. the second and fourth quadrants C. The first quadrant D. the second quadrant
The discussion is divided into two cases: when a + B + C ≠ 0, according to the proportional property of the proportion, we get: k = 2 (a + B + C) a + B + C = 2, then the straight line is y = 2x + 3, passing through the first, second and third quadrants; when a + B + C = 0, namely a + B = - C, then k = - 1, then the straight line is y = - x, passing through the second and fourth quadrants. In conclusion, the straight line must pass through the second quadrant
If there are two double digits A and B, 25 of a is equal to 14 of B, then what is the biggest difference between a and B______ ．
Because a × 25 = B × 14, so a: B = 14:25 = 5:8, because a, B two double digits, a number of 25, that a is a multiple of 5, and a, B is greater than or equal to 10, less than 99; b each maximum 12 is 12 × 8 = 96, and a = 12 × 5 = 60 (exactly a multiple of 5), so the maximum difference between a and B is 96-60 = 36
The application of mean inequality
Isn't the mean inequality to satisfy one positive two definite three phase equality?
Why does the mean inequality have to satisfy the fixed value?
namely
Three phases and so on, which means that the equal sign can not be obtained at the same time when using the mean inequality twice
Can you make it clear
How do you understand without reading
Two definite theory is that two numbers are fixed values, not variables
For example, AB under a + b > = 2 * radical
Then a and B are fixed values, not variables
If and only if a = B, a + B = 2 * under the root sign a, B
The two cars from a to B are 480 km in length, facing each other. After 4 hours, they meet and are 40 km away from the destination
Speed sum: 480 △ 4 = 120 km / h
Speed difference: (40 + 40) △ 4 = 20 km / h
Slow speed: (120-20) △ 2 = 50 km / h
Express speed: 120-50 = 70 km / h
Ask a high one inequality
It is known that the solution set of inequality | x-4 | + | x-3 | < A on the real number set is not an empty set, so we can find the value range of positive number a
The geometric meaning of absolute value, | x-a | represents the distance from point x to point a on the number axis,
So | x-4 | + | x-3 | is the sum of the distances from X to 4 and 3
Obviously there is a minimum of 1
So a > 1
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