Is the proportional relationship between current and resistance in parallel circuit I1: I2: I3 = R3: R2: R1 correct

I=U/R
So the current is inversely proportional to the resistance
I1:I2=R2:R1
That's not right
You use Ohm's law to deduce that how old you are, you can only get older one by one

If three resistors are connected in parallel and R1: R2: R3 = 1:2:3, then I1: I2: i3=

Parallel current = inverse ratio of resistance
So I1: I2: I3 = 1:1 / 2:1 / 3 = 6:3:2

In the circuit shown in the figure, it is known that US = 9V, is = 3A, R1 = 3 Ω, R2 = 6 Ω. Try to find the current I1 and I2 based on the superposition principle, calculate the power of each component, and explain which one is

Is=I1+I2=3A
I2*R2=I1*R1-Us
6*I2=-9+3*I1==>I1=2*I2+3
==>I2=0A,I1=3A
==>Pr1=3A*3A*3=27W
Pr2=0W
Us is the power supply

What is the formula for calculating the volume of a cone?

V＝πh(R2＋Rr＋r2)/3
R - upper and lower radius
R - bottom radius
H-high

The relationship between the existence of the second order partial derivative of a function of two variables and the continuity of the function at this point

F (x, y) = (x ^ 2Y) / (x ^ 4 + y ^ 2), not at the origin, f (0,0) = 0. Easy to calculate
Partial f / partial x = (2XY ^ 3-2yx ^ 5) / (x ^ 4 + y ^ 2) ^ 2, not at the origin, partial f / partial x (0, 0) = 0, can continue to calculate the second order partial derivative
F (x, y) is discontinuous at the origin

Why is density a property of matter in physics

For the same substance, the ratio of mass to volume is the same; for different substances, the ratio of mass to volume is generally different
This shows that the ratio of mass to volume is a property determined by the kind of substance
In physics, density is introduced to express this property
Therefore, density is a physical quantity that represents the characteristics of matter

There should be explanations and formulas
The grass on the grassland can feed 20 cows for five days and 16 cows for six days. How many days can it feed 11 cows?

Step: first, set a cow to eat one portion a day
1、 First, find two total quantities, 20 × 5 = 100, 16 × 6 = 96
2、 Then divide the total difference by the time difference (100-96) and (6-5) = 4 (grass speed)
3、 Total amount plus (because of the decrease of grass speed) grass speed and corresponding days = original grass amount:
100 + 4 × 5 = 120
4、 Divide the original grass amount by (total number plus grass speed): 120 divided by (11 + 4) = 8 (days)
A: 11 cows eat in 8 days

Log2 (x + 4) = 3 ^ x, the number of real roots is?

Calculation: 39 × 37-13 × 34=______ ．

39 × 37-13 × 34 = 39 × 37-13 × 3 × 33 = 39 × (37-27) = 390

The least common multiple of odd and even numbers is the product of the two numbers______ (judge right or wrong)

If an even number and an odd number are coprime, then the least common multiple of the two numbers is the product of the two numbers, such as 8 and 5. If they are not coprime, then the least common multiple of the two numbers is not the product of the two numbers, such as 10 and 15

Is the proportional relationship between current and resistance in parallel circuit I1: I2: I3 = R3: R2: R1 correct