6B-A=7 3A+B=-2

6B-A=7 3A+B=-2

Multiply by three
18b-3a = 21
Two in one
We get 19b = 19
b＝1
a＝－1

Given three points a (- 1,2), B (3,4), C (- 2,5), find the linear equation of the vertical line of the line passing through point a and passing through two points B and C

First, set up an equation, and substitute the coordinates of B. C two points into a series of binary linear equations to solve the linear equation
Let's set another equation. The slope is the negative reciprocal of the slope of the previous straight line, and substitute the coordinates of point a into the solution to get the intercept. It's not convenient to write on mobile phones. The final answer is y = 5x + 7

One degree of electricity can light a 25 watt bulb for several hours

40 hours

It is known that the domain of function f (x) = x + 1 x − 2 is set a, and the domain of function g (x) = LG [X2 - (2a + 1) x + A2 + a] is set B. (I) find sets a and B respectively; (II) if a ∪ B = B, find the value range of real number a

(I) the function f (x) = x + 1 x − 2 is meaningful, it must be x + 1 ≥ x − 2 ＞ 0, the solution is x ＞ 2, the domain of function definition: a = {x | x ＞ 2}, the function g (x) = LG [X2 - (2a + 1) x + A2 + a] is meaningful, it must be X2 - (2a + 1) x + A2 + a ＞ 0, the solution is b = {x ＜ a or X ＞ a + 1}, so the domain of function definition: B = {x ＜ a or X ＞ a + 1}, (II) from a ∪ B = B, then a ⊆ B, so a + 1 ≤ 2, the solution is a ≤ 1 The value range of a is (- ∞, 1]

Because of the formula I = V / R, in household appliances, is the current to resistance to current ratio of computer 220 V?
So the resistance of TV is different from that of computer. Is that right?
The current of relatively small electrical appliances, then not with home power consumption?
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The formula I = u / R is for pure resistance. Computer or TV is not pure resistance, it contains coil and capacitor, so the above formula cannot be used for the whole computer or TV

It's not 2012. It's all the same anyway. Remember that the price is 6 yuan

Well, I've forgotten for six years... So many words, many people want to let others tell themselves the answer on the Internet. Some of them really find the answer. The fifth grade is about to graduate, so I'd better study hard by myself

A DC motor, marked with 36V, 24W words, measured the resistance of the motor coil is 20 ohm, find out the maximum efficiency of the motor in normal operation

I=24/36=2/3 A
Coil heating power P = I * I * r = 8.89w
Efficiency = (24-8.89) / 24 = 62.96%

Simple calculation of 8.37 × 1.2-8.37 × 0.2

8.37*(1.2-0.2)

Does fruit battery convert chemical energy into electric energy or internal energy into electric energy?

Chemical energy into electrical energy, all batteries are chemical energy into electrical energy

1. The square root of a positive number a is 3x-4 and 2-x. what is a? 2. It is known that real numbers a and B are opposite to each other, real numbers C and D are reciprocal to each other, and the reciprocal of real number m is equal to itself. Find CD + (a + B) m - {the absolute value of M}. 3. The area of a pool with a square bottom is 486m cubic, and the pool depth is 1.5m, Will be a few count a few will also leave the answer. 555555 within today will ask math experts to help

1,3x-4 = - (2-x) so a = 1
The reciprocal of 1 and - 1 is 1, so the result is 0
3486 △ 1.5 = 324 is the area of the bottom, because the bottom is square, so the side length of the bottom is 18m