A word or idiom whose pronunciation is mi The more, the better

A word or idiom whose pronunciation is mi The more, the better

Stubborn, complicated, confused, confused, lost, blinding, dazzled, dazzled, dazzled, dazzled, knowing but not returning

The third word is the idiom of "word" and the fourth word is the idiom of "word"

There are 420 kilometers to and fro uphill and downhill. The speed of a car is 30 kilometers when uphill and 42 kilometers when downhill. The average speed of this car is per hour

It took 420 / 30 hours to get up the mountain
It took 420 / 42 = 10 hours to go down the mountain
It took 14 + 10 = 24 hours to walk 420 * 2 = 840 km
So the average speed is 840 / 24 = 35 km / h

2a(x-y)^2+4a^2(y-x)^3

2a(x-y)^2+4a^2(y-x)^3
=2a(y-x)^2+4a^2(y-x)^3
=2a(x-y)^2(1+2a(y-x))
=2a(x-y)^2*(2ay-2ax+1)

The road between the two towns is 180 kilometers long. Xiao Li has driven 20 kilometers, sharing 2 liters of gasoline. According to this calculation, how many liters of gasoline are needed to complete the whole journey?

2 ／ 20 × (180-20) = 2 ／ 20 × 160 = 16 (liter) answer: according to this calculation, you need 16 liters of gasoline to complete the whole journey

If α∈ [0,2 π], find sin α

Sin α & lt; Cos α sin α - cos α & lt; 0sin α · √ 2 / 2 - √ 2 / 2 · cos α & lt; 0sin α · cos (π / 4) - sin (π / 4) · cos α & lt; 0sin (α - π / 4) & lt; 0 ∵ α ∈ [0,2 π] √ - π / 4 ≤ α - π / 4 ≤ 7 π / 4sin (α - π / 4) & lt; 0 get - π / 4 ≤ α - π / 4 & lt; 0

The construction site uses three-thirds of the cement in two days, and two-thirds of the cement in the first day in the second day. How many tons of cement are used in the two days?
First, the solution of the equation, then the proportional solution

If x tons are used in the first day, 2 / 3x tons will be used in the second day, and cement will be used in total
x+2/3x=3/2
The solution is x = 9 / 10
Then 9 / 10 tons and 3 / 5 tons of cement will be used in two days respectively

Why can't a 2n (n + 1) number be expressed as the square difference of two integers?

It is obviously a wrong proposition. For example, when n = 4, 2n (n + 1) = 40 = 7 ^ 2-3 ^ 2

(1) 120 tons of such concrete should be prepared,
How many tons of each of the three materials?

(1) to prepare 120 tons of such concrete, how many tons of each of the three materials are needed?
Cement 120 × 2 / (2 + 3 + 5)
=120×1/5
=24 tons
Huangsha 120 × 3 / (2 + 3 + 5)
=120×3/10
=36 tons
Stone 120 × 5 / (2 + 3 + 5)
=120×1/2
=60 tons

Given the real number R ≠ 0, the function FX = (2x + R, x)

The solution is f (1-r) = f (1 + R),
Knowledge order r = 2
That is, f (- 1) = f (3)
That is, 2 × (- 1) + r = - 3-2R
That is 3R = - 1
The solution is r = - 1 / 3