It is known that a and B are the radii of two circles (and a ≠ b), and C is the center distance of two circles. If the equation x2-2ax + B2 = C (B-A) has equal roots, then a and B are the radii of two circles

It is known that a and B are the radii of two circles (and a ≠ b), and C is the center distance of two circles. If the equation x2-2ax + B2 = C (B-A) has equal roots, then a and B are the radii of two circles

If the equation x & sup2; - 2aX + B & sup2; = C (B-A) has equal roots, then the discriminant is equal to 0, and the solution is a & sup2; - B & sup2; + BC AC = 0, that is, (a-b) (a + B-C) = 0, so C = a + B, two circles circumscribed

It is known that the equation x2 + y2-2 (T + 3) x + 2 (1-4t2) y + 16t4 + 9 = 0 represents the range of T for a circle

X2 + y2-2 (T + 3) x + 2 (1-4t2) y + 16t4 + 9 = 0 [x - (T + 3)] ^ 2 + [y + (1-4t ^ 2)] ^ 2 = - 16t ^ 4-9 + (T + 3) ^ 2 + (1-4t ^ 2) ^ 2, then - 16t ^ 4-9 + (T + 3) ^ 2 + (1-4t ^ 2) ^ 2 〉 0-16t ^ 4-9 + T ^ 2 + 6T ^ 9 + 1-8t ^ 2 + 16t ^ 4 > 0-7t ^ 2 + 6T + 1 > 07t ^ 2-6t ^ 1

The range of ammeter is 0 to 0.6A, the range of voltmeter is 0 to 15V, the resistance R0 = 30 ohm, and the voltage u at both ends of the circuit remains unchanged

When voltmeter = 0, ammeter = 0
When voltmeter = 15V, ammeter = 0.5A
That is to say, when the voltage U changes from 0 to 15, the current changes from 0 to 0.5A
When u does not change, the ammeter does not change

Hurry up! Two math problems in junior two
1. For a quadratic equation of one variable, the sum product of the two is - 14, and the two roots can be obtained
2. Someone bought 1000 yuan bonds for a fixed period of one year. After the maturity, he spent 440 yuan. Then he bought all the remaining money for the bonds for a fixed period of one year. After the maturity, he cashed 624 yuan and asked for the annual interest rate of the bonds
It's a process······
Online, etc······

1. Let two of the equations be X1 and X2 respectively
x1+x2=-14 ①
{
x1*x2=-14 ②
The solution is: X1 = - 7 + 3 √ 7, X2 = - 7-3 √ 7
2. Let the annual interest rate of this bond be X
【1000（1+x）-440】(1+x)=624
(1000+1000x-440)(1+x)=624
1000+1000x-440+1000x+1000x^2-440x=624
1000x^2+1560x-64=0
That is: 125x ^ 2 + 195x-8 = 0
(25x-1)(5x+8)=0
X1 = 1 / 25 = 4%, X2 = - 8 / 5 (rounding off)
A: the annual interest rate of this bond is 4%

The output power of a small hydropower station is 20kW, and the total resistance of the transmission line is 0.5 ohm. If the transmission voltage is 400V first and then 2000V, the change of the power loss on the transmission line after the transmission voltage is increased is as follows:
A. 50W reduction
B. Reduce 1200W
C. Decrease by 7.68 * 10 ^ 6W
D. Increase by 7.68 * 10 ^ 6W
What are the specific steps

First, the voltage is 400V
Then the current I = P / u = 20000 / 400 = 50
Power loss on transmission line = I ^ 2 * r = 50 ^ 2 * 0.5 = 1250W
Switch to 2000V voltage transmission
Then the current I = P / u = 20000 / 2000 = 10
Power loss on transmission line = I ^ 2 * r = 10 ^ 2 * 0.5 = 50W
So the electric power is reduced by 1250-50 = 1200
Choose B

Collect the beautiful 600 word composition of life

The beautiful life of collecting life is not lack of beauty, but lack of eyes to find beauty. At this time, we are in the Jingjing campus. Some people say that such a life is boring, but it is not. As long as we observe it carefully, there are beautiful scenery everywhere. It was an autumn morning, and the teacher was on the platform to impart knowledge endlessly

Is the work done by Ampere force always equal to Joule heat in quantity

When the conductor moves under the action of Ampere force, the ampere force does work on the conductor, but this part of work is specialized for the mechanical energy of the conductor. Joule heat is the work done by the current

If integers a and B satisfy a & # 178; = 2B, B & # 178; = 2A, then what are the values of a and B? (except 2)

a²=2b
Square on both sides
a^4=4b²
b²=2a
a^4=8a
a^4-8a=0
a(a³-8)=0
a(a-2)(a²+2a+4)=0
a≠2
There is no solution for a & # 178; + 2A + 4 = 0
So a = 0, B = 0

A motor, with a resistance of 10 ohm, is used in the lighting circuit, and the current passing through is 5 amperes. What is the power consumption of the motor? What is its heating power? What is the power converted into mechanical energy? How efficient is the motor? If the weight of the object is 8500 Newton, what is the rising speed of the object?

(1) The voltage of lighting circuit u = 220 V, the electric power consumed by motor P = UI = 220 V × 5A = 1100 W; (2) the heating power of motor P = I2R = (5a) 2 × 10 Ω = 250 W; (3) the mechanical power of motor P = P-P heat = 1100 W-250 w = 850 W; (4) the efficiency of motor η = w Machine w × 100% = 850 W11

If a particle moves in a uniformly accelerated straight line with zero initial velocity, its displacement in the second second second is 6 m, then its displacement in the fifth second is 6 m
It's like the teacher told me to use 1:3:5:7 in class. I forgot to ask for advice,

S = v0t + 1 / 2at ^ 2, then the displacement in the first second is 1 / 2a, the velocity in the first second is a, the displacement in the second second second is a + 1 / 2a, the velocity at the end of the second second second is 2a, and the displacement in the third second second is 2A + 1 / 2A The displacement ratio above neutralization is 1:3:5:7