If x = 1y = − 2 is a solution of the equation AX by = 1 about X and y, and a + B = - 3, then 5a-2b=______ ．

If x = 1y = − 2 is a solution of the equation AX by = 1 about X and y, and a + B = - 3, then 5a-2b=______ ．

Substituting x = 1y = − 2 into the equation AX by = 1, we get a + 2B = 1. Because a + B = - 3, we get the binary linear equation system a + 2B = 1A + B = − 3 about a and B. solving this equation system, we get b = 4, a = - 7, so 5a-2b = 5 × (- 7) - 2 × 4 = - 35-8 = - 43

The solution of the equation 2x - (- x + 6) = 9 is the same as that of (AX + 4) / 5 = - 1, so we can find the value of 5A + 9

2x-（-x+6）=9
2x+x-6=9
3x=15
x=5
Same solution
If we substitute x = 5 into (AX + 4) / 5 = - 1, we get
(5a+4)/5=-1
5a+4=-5
5a=-9
a=-9/5
∴5a+9=-9+9=0

Given the equation | x | = ax + 1, when the value of a is, the equation has a positive root and a negative root
I am only in grade one of junior high school. I have learned bivariate linear equation and univariate linear inequality. Please answer this question according to my existing knowledge

|X | = ax + 1, square of both sides
x^2=a^2x^2+2ax+1
(a^2-1)x^2+2ax+1=0
The equation has a positive root and a negative root
x1*x2

If the square of (a + 2) and | B + 1 | are opposite to each other, find the square of 5ab - {the square of 2A - [the square of 3AB - (4AB)

A + 2 = 0 and B + 1 = 0
a=-2,b=-1
5ab^2-[2a^2b-(3ab^2-4ab)]=-10-[-8-(-14)]=4

A car is driving from place a to place B at the speed of 120 km / h, while a bus is driving from place B to place a at the speed of 1010 km / h
How many kilometers is the total length of a and B?

Let x (x + 12.5) / 1010 = (x-12.5) / 120, x = 15.9km, total length 31km

If a > 3, then | A-3|=______ ，|3-a|=______ ．

∵ a > 3, ∵. A − 3 & nbsp; & nbsp; = A-3,. 3 − A & nbsp; & nbsp; = A-3, so the answer is: A-3, A-3

The bus takes 10 hours from a to B, and the train takes 15 hours from B to a. the two trains leave each other at the same time. When they meet, car a travels 90 kilometers more. When they meet, how many lanes are there

If the distance between the two places is x, the speed will be x / 10 and X / 15 respectively. The time for meeting is x / (x / 10 + X / 15) = 6 hours. Then (x / 10-x / 15) * 6 = 90, the solution is x = 450.6 * 450 / 10 = 270 and 6 * 450 / 15 = 180

In 1,2,3,4,5.499500. How many times does the number "2" appear in these numbers
How to do it?

57

High school physics mechanics
On the horizontal table, push an object with force F. after the object moves s meters from the initial speed of 0, it suddenly removes the external force F, and then the object slides for 3 seconds and stops to find out the friction force F. the reference answer is f / 4. But I think this is a wrong question, because I bring the answer in and find that the moving time of s meters in front is - 1 second. Please help me

Yes, this problem is wrong. We should change s meter to 1s (one second). It can be solved quickly by the momentum theorem. (f-f) * 1 = MV
f*3=mv
The solution is f = f / 4

1. 20% of a number is less than 60% of its half. Find the difference between equation 2, 3 / 2 and 1 / 2 of the number and multiply by 5 / 9 and 3 / 7
What is the sum product

1 60÷(1/2-20%)
=60÷3/10
=200
2 (3/2-1/2)×(5/9+3/7)
=1×62/63
=62/63
This is my conclusion after meditation,
If not, please ask, I will try my best to help you solve it~
If you are not satisfied, please understand~