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The monotone decreasing interval of the function y = log12 (− x2 + 6x − 8) is () A. [3，4）B. （2，3]C. [3，+∞）D. [2，3]
Let y = log12 (− x2 + 6x − 8) = log12t, t = - x2 + 6x-8, then the equation of the axis of symmetry of the parabola t = - x2 + 6x-8 is t = 3. On the parabola t = - x2 + 6x-8, the increasing interval is (2,3), the decreasing interval is [3,4], ∵ y = log12t is the decreasing function, ∵ y = log12t is the decreasing function
The number of female employees in a company is 18 less than 3 / 5 of the total number, while the number of male employees is 5 / 3 of that of female employees. How many employees are there in this company?
Women account for 1 / 8 (1 + 5 / 3) = 3 / 8 of the total
So a total of 18 (3 / 5-3 / 8) = 80 people
X ^ 2-y ^ 2 + MX my 5x ^ 5-15x ^ 3-20x cross multiplication factorization
X ^ 2-y ^ 2 + MX my this is a
5x ^ 5-15x ^ 3-20x this is another way
x^2-y^2+mx-my=x^2+mx-y^2-my=x^2+mx+1/4m^2-y^2-my-1/4m^2=(x+1/2m)^2-(y+1/2m)^2=(x-y)(x+y+m)
5x^5-15x^3-20x=5x(x^4-3x^2-4)=5x(x^2-4)(x^2+1)=5x(x-2)(x+2)(x^2+1)
There are 25 boys in class 51. Boys account for 5 / 9 of the class. How many are there in the class?
25 divided by 5 / 9 = 45
Let X and y satisfy x2 + 2xy-1 = 0, then the value range of X + y is______ ．
∵ x2 + 2xy-1 = 0 ∪ (x + y) 2 = 1 + Y2 ≥ 1, then x + y ≥ 1 or x + y ≤ - 1, so the value range of X + y is (- ∞, - 1] ∪ [1, + ∞), so the answer is: (- ∞, - 1] ∪ [1, + ∞)
There are 350 students in the fourth grade of Hongqi primary school, and the number of students in the fifth grade is six seventh of that in the fourth grade,
How many people
There are 350 students in the fourth grade;
Grade 5: 350 × 6 / 7 = 300
Grade 6: 300 × 5 / 6 = 250
How much is 5 after prescribing? Thank you
2.236.
The sum of a, B and C is 80. The number of a is twice that of C, and the number of B is three times that of C. what are the numbers of a, B and C?
C is 8
After the denominator of equation х / 2 - (x-1) / 3 = 1 is removed, the equation obtained is?
3x-2(x-1)=6
x=4
The sum of a and B is 120. The number of a is two fifths more than that of B. find the number of B
We should synthesize the formula
Number b = 120 (1 + 1 + 2 / 5) = 50
RELATED INFORMATIONS
- 1. Given a > 1, ab = 2A + B, then the minimum value of (a + 1) (B + 2) is______ ．
- 2. It is known that in trapezoidal ABCD, ad ∥ BC, median line EF intersects AB with F, intersects AC, BD with m, N, EF = 120, Mn = 80, find the length of AD and BC
- 3. Define a new operation: m # n = Mn + m + N, then 1 # 2 # 3 #How many different calculation results can be obtained by adding several pairs of brackets to 10?
- 4. There is a kind of fruit, yellow. It's a bit like banana, but it's twice as small as banana. It doesn't have thick skin like banana, and it still has a bad smell What kind of fruit is it? .
- 5. LIM (x tends to negative infinity) ((x ^ 2 + 1) ^ 1 / 2 + x) how to do?
- 6. Let L and m be two non perpendicular straight lines with different surfaces, and try to prove that the surface generated by the rotation of the straight line m around the straight line L is a hyperboloid with one sheet
- 7. How many meters is 100 square meters
- 8. What is LIM (x → 0) 2x + △ x? Why?
- 9. Is there an expression for electric energy
- 10. 1. For a job, team a will do it alone in 8 days and team B will do it alone in 10 days. How many days will the two teams work together to complete it? 2. A project. Team a works alone for 12 hours and team B works alone for 15 hours. If the two teams work together for 2 hours and then Party B works alone, how many hours will it take to complete? 3. A manuscript can be completed in 12 hours by two typists of a and B. how many hours does it take for a typist of a to type alone and for a typist of B to type alone? 4. A local train and an express train leave from station a and station B at the same time. After meeting for 20 hours, it will take 30 hours for the local train to reach station B, and how many hours for the express train to reach station a? Please write down the process clearly
- 11. The natural number 1 times 2 times 3 times 998 times 999 times 1000 has a zero at the end of the product
- 12. Proving 1 ^ 3 + 2 ^ 3 + 3 ^ 3 + by mathematical induction n^3=（1+2+3+.+n)^2
- 13. Calculate [1 / 3-1 / 2] + [1 / 4-1 / 3] + [1 / 5-1 / 4] + +【1/2004-1/2003】
- 14. In △ ABC, a = 80, B = 100, a = 30 °, then the number of solutions of B is () A. 0b. 1C. 2D. Not sure
- 15. Who has the exercises of biology in grade one! Note: good topic! Because I want to sharpen my gun!
- 16. As shown in the figure, one end of the light rod with length L = 0.5m is fixed with a small ball with mass m = 0.1kg, and the other end is fixed on the rotation axis O. the small ball rotates uniformly on the horizontal plane around the axis, and the light rod turns 30 degrees every 0.1s. (π ^ 2 = 10) (1) try to find the centripetal acceleration of the small ball. (2) centripetal force of the small ball
- 17. The difference between X and 3.2 is 4.8?
- 18. How to solve the equation 41-x = 4 (14-x)
- 19. Less than 4 / 5 of a number, 7 / 8 is 1 / 48 of 6. Find the number
- 20. 1. Solve the following equation and test. X + 0.3 = 1.83 + x = 5.4x-1.5 = 4x-6 = 7.6