There is a column of numbers arranged in a certain order: 2, - 4, 8, - 16, 32, - 64 According to this rule, write the number of the nth term______ (★ friendly tips: it can be expressed in the form of power, to be tested)

There is a column of numbers arranged in a certain order: 2, - 4, 8, - 16, 32, - 64 According to this rule, write the number of the nth term______ (★ friendly tips: it can be expressed in the form of power, to be tested)

The first term is 2, the second term is (- 2) × 2 = 4, the third term is (- 2) × (- 4) = 8, and so on, we can know that it is an equal ratio sequence, and the common ratio q = - 2; thus we can know that an = A1 · QN-1, so the N term is 2 × (- 2) n-1, which is reduced to (- 1) n-1 · 2n, so the answer is (- 1) n-1 · 2n

-2,4, - 8,16, - 32,64. According to what rule?

The latter number is negative double of the former

Is the conversion of lithium battery into electric energy a chemical change
If you answer carefully, you will be rewarded

It's a chemical reaction
The discharge process of lithium battery is redox reaction, Li + MnO 2 = LiMnO 2, there are chemical bonds breaking and forming, so it is chemical reaction

Simple calculation of 1-1 / 3 + 7 / 12-9 / 20 + 11 / 30-13 / 42

1-1/3+7/12-9/20+11/30-13/42
=1-1/3+1/3+1/4-1/4-1/5+1/5+1/6-1/6-1/7
=1-1/7
=6/7

When it rises to a certain point P, the kinetic energy is reduced to 10J and the mechanical energy is lost by 10J. If the air resistance is constant, the kinetic energy of the object falling back to the throwing point is______ ．

Let G be the gravity of the object, f be the air resistance, H be the height from the ejecting point to P, and H be the height from the ejecting point to the highest point

A simple calculation + 5 / 2 / 2 / 2
+1 / 5 - 1 / 2 - 1 / 2

+1 / 5 - 1 / 2 - 1 / 2
=1 / 5 - 1
=-4 out of 5

There is an ammeter with an internal resistance of 1K ohm and a full bias current of 50ua. Now, if we want to refit it into an ammeter with a range of 1mA, how much resistance do we need in parallel?

Refit the ammeter into a shunt resistor, I = I1 + I2 = 50 * 10 ^ - 6 + I2 = 1 * 10 ^ - 3, I2 = 950 * 10 ^ - 6a, u = I1 * R1 = 1000 * 50 * 10 ^ - 6 = 50 * 10 ^ - 3V, i2r2 = 950 * 10 ^ - 6 * R2 = 50 * 10 ^ - 3, R2 = 52.63 ohm

The distance between station a and station B is 850 km. One slow train departs from station a to station B at 6 a.m. and the other express train departs from station B to station a at 7 a.m. it is known that the express train travels 10 km more per hour than the slow train. When can the two trains meet at the place where the express train exceeds the midpoint of 25 km?
(that's all,

Suppose the speed of the slow train is x km / h, then the speed of the fast train is x + 10 km / h. When the slow train meets, it runs for y hours, because the two trains meet at the place where the fast train exceeds the midpoint of 25 km. The distance from station a is 400 km, and the distance from station B is 450 km
xy=400
（x+10）（y-1）=450
The solution is x = 40, y = 10
So at 4 p.m., the two cars met 25 kilometers above the midpoint of the express

How to understand the power source in physical electricity is to convert other forms of energy into electrical energy
Try to give a real-life example

The power supply includes dry battery, storage battery, generator and so on
Dry battery and storage battery are converted from chemical energy to electric energy
Generator depends on the form of generator, including wind power, thermal power, nuclear power, solar power, geothermal power, tidal power and so on~

Life is a teacher's composition, 800 words

Life is like a treasure box full of pearls, which is full of our achievements: the teacher's instruction; the conflict between classmates; the truth of life There are our attentive listening, our conflicts and our life experience But all of this, it all comes from her When we're still in the teeth