The application of Ohm's law in Physics Connect a 5-ohm resistor R1 and a 15 ohm resistor R2 in series, and connect them to a 6V power supply. What is the current in the series circuit? (the format should be standard ~)

This is a series circuit
Total R = R1 + R2 = 15 + 5 = 20 (Euro)
According to Ohm's law,
I=6/20=0.3（A）
The current in this series circuit is 0.3A

As shown in the figure, the voltage at both ends of the power supply remains unchanged, and RO is the constant resistance. When the slide P is placed in the middle point and only S1 is closed, the indication of the voltmeter is u and that of the ammeter is I. in the following cases, the correct change of the indication of the voltmeter and current is ()
A. When slide P does not move, when S1 is opened and S2 and S3 are closed, the voltage indication number remains unchanged and the current indication number decreases. B. when slide P does not move, when S1 is opened and S2 and S3 are closed, the voltage indication number increases and the current indication number increases. C. when only S1 is closed and slide P moves from the midpoint to the right, the voltage indication number increases and the current indication number decreases. D When only S1 is closed and slide P moves from the midpoint to the right, the voltage representation remains unchanged and the current representation becomes larger

① When the slide P does not move, open S1 and close S2 and S3, the sliding rheostat is connected in parallel with the fixed resistance ro. At this time, the voltmeter measures the voltage at both ends of the sliding rheostat, and the ammeter measures the current through the sliding rheostat, as shown in Figure 1. It can be seen from the figure that in the state of Figure 1, the ammeter measures the current through the sliding rheostat, that is, the resistance of the branch is r-slip, while the power supply is r-slip In the state of Figure 1, the voltmeter measures the power supply voltage, and its indication is u, which means the indication of the voltmeter becomes larger. Therefore, a does not conform to the meaning of the problem, and B conforms to the meaning of the problem. ② when S1 is only closed and slide P is placed at the midpoint, the setting resistance ro is connected in series with the sliding rheostat, and the voltmeter measures both ends of the sliding rheostat In the state of Figure 2, the constant resistance ro is connected in series with the sliding rheostat, the voltmeter measures the voltage at both ends of the sliding rheostat, and the ammeter measures the current in the whole circuit. When the slide P moves from the midpoint to the right, the resistance of the sliding rheostat connected into the circuit becomes smaller According to Ohm's law I = ur, the current in the circuit becomes larger, that is, the indication of the ammeter becomes larger. The resistance of the constant resistance ro remains unchanged. According to the formula u = IR, the voltage at both ends of the constant resistance ro becomes larger. According to the voltage characteristics of the series circuit, the voltage at both ends of the sliding rheostat becomes smaller, that is, the indication of the voltmeter becomes smaller And d do not fit the meaning of the question

Given A2 + B2 = 25, a + B = 7, find A-B, AB, A2-B2

This is the first time that we want to be able to get 178; (b) we want to get 178; (B \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\9-16 = - 7 or 16-9 = 7

Given that A.B.C is a real number, f (x) = ax ^ 2 + BX + C, when - 1 "X" 1 is, there is always | f (x) | 1. (1) prove | C | 1, | B | 1
Given that A.B.C is a real number, f (x) = ax ^ 2 + BX + C, if - 1 "X" 1 is, there is always | f (x) | 1
(1) Verification of | C | 1, | B | 1
(2) Verification of | f (x) 8
Sorry, I have the wrong number.
Is to verify: | f (2) | 8

(1)f(0)=c,-1

On factorization
（1）48x²+22x-15
（2）21x²+31x-42
（3）35x²+23x-6
（4）(x+y)²-5（x²-y²）+6（x-y）²
（5）4x²-14xy+6y²-7x+y-2
I racked my brains and couldn't figure out these five problems. I used common factor method, formula method and cross multiplication to solve them

(1) 48x & sup2; + 22x-15 original formula = (8x-3) (6x + 5) multiplication by cross: 8 - 36 5 (2) 21x & sup2; + 31x-42 original formula = (7x-6) (3x + 7) 7 - 63 7 (3) 35x & sup2; + 23x-6 original formula = (7x + 6) (5x-1) 7 65 - 1 (4) (x + y) & sup2; - 5 (X & sup2; - Y & sup2;) + 6

Given that the vertex coordinates of the image of a quadratic function are (- 1.1), find the quadratic function relation
Passing through the origin

y=a(X+1)^2+1
One more condition is needed to determine the relation

x²=20+8x

x²=20+8x
x²-8x-20=0
(x-10)(x+2)=0
∴x1=-2,x2=10
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The intersection points of the quadratic function y = x ^ 2-2x + K and X axis are on the right side of the origin, and the value range of K is in the range
According to speed + min

Let f (x) = x ^ 2-2x + K
The opening of function image is upward, and there are two intersections with X axis, and the discriminant is greater than 0
△=4-4k＞0
k＜1
f(0)>0
k>0
In conclusion, 0 < K < 1

A practical problem, a formula,
The upper part of the tunnel entrance is a semicircle, and the lower part is a rectangle. It is known that the length of the rectangle is 10 meters and the width is 5 meters. What is the perimeter and area of the cross section of the tunnel?

A rectangle is 10 meters long and 5 meters wide,
Then s rectangle = 5x10 = 50
Then l rectangle = 2x5 + 2x10 = 30
If the length of the rectangle is 10 meters, then the diameter of the semicircle of the tunnel is 10, then the radius is 5, then
S semicircle = 0.5x25 Π
L semicircle = 5 Π
Perimeter of tunnel cross section = 30 + 5 Π (m)
Cross sectional area of tunnel = 50 + 0.5x25 Π (M2)

Four times of the distance from the moving point to the y-axis is equal to the square of the distance from the moving point to the point a (1, - 3)
Do not understand!

Let the coordinates of the moving point be (x, y)
According to the meaning of the title
When (x0)
It's OK to join the above
Note: the superscript of square is hard to type, so I use Chinese characters instead
If we don't discuss the positive and negative absolute values, we have to square them too much
Has been very detailed, the specific problem-solving steps are all written on the omission of the simplification process
The same is true for x0

The application of Ohm's law in Physics Connect a 5-ohm resistor R1 and a 15 ohm resistor R2 in series, and connect them to a 6V power supply. What is the current in the series circuit? (the format should be standard ~)