A 960 square meter flower bed is planned to plant three kinds of flowers and plants, rose flower 240 square meters, and the rest is planted with holly and chrysanthemum at a ratio of 7:5 How many square meters are planted?

A 960 square meter flower bed is planned to plant three kinds of flowers and plants, rose flower 240 square meters, and the rest is planted with holly and chrysanthemum at a ratio of 7:5 How many square meters are planted?

Holly planting = (960-240) * 7 / (7 + 5) = 420 M2
Chrysanthemum planting = (960-240) * 5 / (7 + 5) = 300 square meters

What percentage of the planting area of various flowers respectively? There are 50 squares of flower beds, 15 squares of Impatiens, 10 squares of tulips and 15 squares of rose

Impatiens 15 / 50 * 100% = 30%
Tulip 10 / 50 * 100% = 20%
Rose 15 / 50 * 100% = 30%

Given the ellipse 9x & # 178; + 16y & # 178; = 144, how can it be transformed into a standard equation

By dividing both sides of the equation by 144, we get X & # 178 / 16 + Y & # 178 / 9 = 1

⊥ 40 [1 / 2] the full bias current of an ammeter I = 500 mA, the internal resistance R = 2.5 Ω, a resistor of what resistance value should be connected in series, at this time, the internal resistance of the voltmeter is more
⊥ 40 [1 / 2] the full bias current of an ammeter is I = 500mA, and the internal resistance is r = 2.5ohm. What is the resistance in series? What is the internal resistance of the voltmeter? When the modified ammeter is connected to the circuit, the meter indicates 100 ohm

If so, I = 100 / (2.5 + R). 2.5 + r = 200, r = 200-2.5 = 197.5 Ω

It is known that x = 1 is a solution of the quadratic equation AX & # 178; + bx-10 = 0, if a and B are not equal to 0
The value of a-178; - b-178 / 2a-2b is,

X = 1 is substituted into the equation
a+b-10=0
a+b=10
(a²-b²)/(2a-2b)
=(a+b)(a-b)/[2(a-b)]
=(a+b)/2
=10/2
=5

What is the difference between insulation resistance and volume resistivity

The insulation resistance is the quotient of the DC voltage applied between the electrodes in contact with the sample and the steady-state current passing between the electrodes. It includes volume resistance and surface resistance;
Volume resistivity is the quotient of DC electric field intensity and steady current density in volume current direction, unit: ohmmeter

The judgment function f (x) = - X & # 178; + 1, X belongs to the parity of [- 1,2]

The symmetry of the domain D about the origin is a necessary and not sufficient condition for this function to be even
For example: F (x) = x ^ 2, X ∈ R (f (x) equals the square of X, X belongs to all real numbers), then f (x) is even function
. f (x) = x ^ 2, X ∈ (- 2,2)] (f (x) equals the square of X, - 2

The following household appliances work normally for 10 seconds and consume the most electricity ()
A. TV B. laptop C. washing machine D. air conditioner

The power of TV set is about 130W; the power of notebook computer is about 20W; the rated power of washing machine is about 300W; the power of air conditioner is about 1000W. It can be seen that the electric power of air conditioner is the largest. According to w = Pt, the electric energy consumed by air conditioner is the most at the same time when electrical appliances work normally

How to calculate 0.39 × 9.8 + 2 × 3.9?

The title should be: 0.39 × 9.8 + 2 × 0.039? 0.39 × 9.8 + 2 × 0.039 = 0.39 × 9.8 + 0.2 × 0.39 = 0.39 × (9.8 + 0.2) = 0.39 × 10 = 3.90.39 × 9.8 + 2 × 3.9 = 0.39 × 9.8 + 20 × 0.39 = 0.39 × (9.8 + 20) = 0.39 × 29.8

First charging time of lithium battery for electric vehicle

In order to transport safety, lithium trams are all semi charged. After purchasing electric vehicles, they need to charge first. The charging time is more than 10 hours, and the charger can continue to charge after the green light is displayed
Since lithium battery has no memory function, it's better to charge as soon as you ride in the future. Forming the habit of charging in time can improve the life of lithium battery by 2-3 times
When it is not used for a long time, it should be charged once within 90 days, and it should not be stored in the case of power loss
It is strictly forbidden to rain or immerse lithium batteries in water
Before use, please read carefully the notes pasted on the lithium battery