If x = 1, y = - 1 is the solution of the equation AX + 2by = 0, x = a, y = B is the solution of the equation 3x + y = 7, then a = B=

If x = 1, y = - 1 is the solution of the equation AX + 2by = 0, x = a, y = B is the solution of the equation 3x + y = 7, then a = B=

∵ x = 1, y = - 1 is the solution of the equation AX + 2by = 0
∴a-2b=0①
∵ x = a, y = B is the solution of equation 3x + y = 7
∴3a+b=7②
It can be obtained from (2 × 2 + 1)
7a=14
∴a=2
If a = 2, we can get
b=1

Solving the equation AX + BX about X=

ax^2+a^2x+bx^2+b^2x=(a+b)(x^2+ax+bx+ab)
To 2abx = - AB (a + b)
∵ab≠0
∴2ab≠0
x=-(a+b)/2

Given that OA, OB and OC are perpendicular, and OA = ob = OC = 2, calculate the volume of o-abc and the distance from point 0 to horizontal ABC

Volume = 2x2 / 2x2 / 3 = 4 / 3
The distance is 2 / (2 square root)

When we transport a batch of goods, we use 20% for the first time, six tons for the second time, and two tons less than the sum of the previous two times for the third time. At this time, there is still one third of the goods left to be transported. How many tons are there in this batch of goods?

Let's say the total quantity of the goods is x tons
The third shipment: 20% x + 6-2
Three times freight: 20% x + 6 + (20% x + 6-2) = 40% x + 10
x-(40%x+10)=1/3x
The solution is x = 37.5

The maximum value of function y = Log1 / 2 (x + 1 / (x-1) + 1)
Is there no maximum value in this problem

Yide x > 1
True number = (x-1) + 1 / (x-1) + 2 ≥ 4
So when the true number is 4, the maximum value of Y is log (0.5,4) = - 2

There are 28 male workers in a workshop. Male workers are 7 / 9 of female workers. How many female workers are there

There are x female employees
7:9=28：x
x=28x9÷7
x=36
So there are 36

Decomposition factor: (1) x ^ 2y-9y (2) 2A ^ 2-4a + 2 (3) 2x ^ 3-8x (4) 27x ^ 2 + 3

Hello, I'm glad to answer your question
（1）x^2y-9y
=y(x^2-9)
=y(x+3)(x-3)
（2）2a^2-4a+2
=(2a-2)(a-1)
(3)2x^3-8x
=2x(x^2-4)
=2x(x+2)(x-2)
(4)27x^2+3
=3(9x^2+1)

There are 24 students in class 61 who are up to the standard of physical education, accounting for 3 / 5 of the total number of students in the class
What is calculated at each step? You will be rewarded after writing

First, find out the number of people in the whole class 24 △ 3 / 5 = 40
Then, the number of people with 75% compliance rate is 40 * 75% = 30
Finally, 30-24 = 6
Only when six more people reach the standard can the rate of reaching the standard reach 75%

Factorization: 3x ^ 2 + 2xy-8y ^ 2

Multiplication by cross
3x^2+2xy-8y^2
=(3x-4y)(x+2y)

As the National Day is approaching, the school organizes the seventh grade students to participate in the "National Day Special Exhibition". It plans to rent 16 buses with 42 seats, which are just full. However, as 126 students are going to ride bicycles, the school has to change the composition scheme. (1) how many buses should the school actually rent after changing the composition scheme? (2) if the speed of the bicycle is 10km / h, one hour after the start, the school will change the composition scheme, How long did the bus run at a speed of 40 km / h when all the students arrived at the designated place at the same time?

(1) Design and rent x buses 42x = 42 * 16-126 x = 13
(2) Suppose that the driving time is y hours, 40y = (40-10) * 1, y = 3 / 4
So the bus ran for 45 minutes