On the relationship between root and coefficient It is known that the square of the quadratic equation x plus 3x minus 1 equals to 0 are X1 and x2. Please use the relationship between the root and the coefficient to find the absolute value of X1 minus x2 I want the process. Not just answers or theories.

On the relationship between root and coefficient It is known that the square of the quadratic equation x plus 3x minus 1 equals to 0 are X1 and x2. Please use the relationship between the root and the coefficient to find the absolute value of X1 minus x2 I want the process. Not just answers or theories.

X1 + x2 = - B / a = - 3, X1 * x2 = C / a = - 1, the square of x1-x2 bracket = X1 + X2, the square of bracket - 4 * X1 * x2 = 9 + 4 = 13, so the absolute value of x1-x2 = root 13

Exercises on the relationship between the root and coefficient of quadratic equation of one variable
It is known that a and B are two of the equations 2x ^ 2-7x + 2 = 0, and the quadratic equation with a + 1 / B and B + 1 / A as roots is solved

Incandescent lamps with rated voltage of 220 V and power of 100 W and 40 W are connected in series with a 380 V power supply. The actual power of each bulb is calculated, and which bulb will be burned
Write all your formulas, including your ideas!

First, calculate the respective resistance with rated voltage and power: r = square of voltage divided by rated power, 100W and 40W are 484
After series connection, the sum of the two resistors is 1694 Ω;
After connecting to 380V, use Ohm's law to calculate the current, voltage and power
The voltage of 100W and 40W bulb is 108.6v and 271.4v respectively, and the power is 24W and 61W respectively
Because the voltage of 40W bulb is 271.4v, it will burn down

Simple calculation of 5.23 × 4 + 4.77 △ 0.25

5.23×4+4.77÷0.25 =5.23x4+4.77x4 =(5.23+4.77)x4 =10x4 =40
Please accept if you are satisfied

The normal working voltage of a DC motor is 6V, the current is 0.5A, and the resistance of the motor coil is 2 Ω,
When the motor is working normally, there will be___ If you want to change the direction of the motor, the simplest way is to change the direction of the motor_____ .

N total = u i t = 6V * 0.5A * 1 * 60s = 180J, q = I ^ 2 R T = (0.5A) ^ 2 * 2 Ω * 1 * 60s = 30jn mechanical = N Total - Q = 180j-30j = 150j hey, you're welcome

Disjunction calculation 50.4 × 1.9-1.8 & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 3.76 × 0.25 + 25.8

（1）50.4×1.9-1.8，=95.76-1.8，=93.96；（2）3.76×0.25+25.8，=0.94+25.8，=26.74．

How to explain that galvanic cells can convert chemical energy into electrical energy

Electrochemical knowledge takes electrolyte solution as carrier and redox reaction as core. Anode of primary cell and anode of electrolytic cell are oxidation electrode, and cathode of primary cell and cathode of electrolytic cell are reduction electrode

Application of discount sale
The original price of an air conditioner in a shopping mall is 2500 yuan per unit. After the discount, the sales volume can be increased by 10 units. If the sales volume after the discount is 100000 yuan, what is the discount rate?
80%

If the sales volume remains the same, it's just to increase the sales volume. It's not easy. If you use 100000 / 2500 = 40 units, and add 10 units, you'll get 50 units
That is to say, 50 sets sell for 100000. That's 100000 / 50 = 2000 yuan per set. The discount is 2000 / 2500 × 100% = 80%

Chemical energy into electricity is a. hydropower B. wind power c. coal combustion to generate electricity

The answer is C

People's education press second year mathematics exercise book Volume 2 19.2.1 rectangle (1) answer to question 8

Choose B
Reason: the diagonals are equal
Equal base and equal height
Equal area
So it's a quarter