A fruit company urgently needs to transport a batch of fruits that are not easy to store from city a to city B for sale. There are three transportation companies to choose from. The information provided by the three transportation companies is as follows: transportation unit & nbsp; & nbsp; transportation speed (km / h) & nbsp; transportation cost (yuan / km) & nbsp; packaging and handling time (H) & nbsp; packaging and handling cost (yuan) & nbsp; & nbsp; Company a & nbsp; 60 & nbsp; 6 & nbsp; 4 & nbsp; 1500 & nbsp; company B & nbsp; 50 & nbsp; 8 & nbsp; 2 & nbsp; 1000 & nbsp; company C & nbsp; 100 & nbsp; 10 & nbsp; 3 & nbsp; Answer the following questions: (1) if the total cost of packing, loading, unloading and transportation of company B and company C is twice that of company a, find the distance between city a and city B; (2) if the distance between city a and city B is s (km), and the loss of this batch of fruit in the process of packing, loading, unloading and transportation is 300 yuan / hour, then the total cost to be paid by the fruit company (the sum of packing and handling expenses, transportation expenses and loss) is the smallest. Which transportation company should be chosen?

(1) Suppose the distance between a and B is x (km), then the cost of packing, loading, unloading and transportation of the three transportation companies is (6x + 1500) yuan for company a, (8x + 1000) yuan for company B, and (10x + 700) yuan for company C. according to the meaning of the question, (8x + 1000) + (10x + 700) = 2 (6x + 1500), the solution is x = 21623 ≈ 217 (km) The total cost of transportation company is Y1, Y2 and Y3 respectively. The time required for packaging, loading and unloading and transportation of the three transportation companies is (S60 + 4) h for company a, (S50 + 2) h for company B, and (S100 + 3) h for company C. Y1 = 6S + 1500 + (S60 + 4) × 300 = 11S + 2700, y2 = 8s + 1000 + (S50 + 2) × 300 = 14s + 1600, Y3 = 10s + 700 + (S100 + 3) × 300 = 13s + 1600 When s ＜ 550 (km), Y1 ＞ Y3, and ∵ Y2 ＞ Y3, then C company is better. When s = 550 (km), Y2 ＞ Y1 = Y3, then a company or C company is better. When s ＞ 550 (km), Y2 ＞ Y3 ＞ Y1, then a company is better

In the known △ ABC, ∠ a = x °
(1) As shown in Figure 1, if the angular bisectors of ∠ ABC and ∠ ACB intersect at point O, then x is used to express ∠ BOC = 0_ (2) as shown in Figure 2, if the triad of ∠ ABC and ∠ ACB intersects at points O1 and O2, then x is used to express ∠ bo1c = 0_ (3) as shown in Fig. 3, if the N bisectors of ABC and ACB intersect at points O1, O2 , on-1, then use X to express ∠ bo1c = 1___ °

(1) The dividing line of angular bisdividing line of ABC and ACB intersects at point O, where o is the point O, and the \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\0 ∠ o ABC, OCB is the main source of the ABC, which is the "ABC" of the ABC, and the "o1cb" is the 23 ￣ ACB, and the ￣ o1bc is the "ABC, and the \\\\\\\32 \cb = 23 \1cb, and the \\\\\\\\\\1cb \ \ c (1c) (1) (2) from (1) (1) (2) from (1) (1) (n-bisector of and ∠ ACB Intersection at O1, O2 The answer is: (1) 90 + 12x, (2) 60 + 23x, (3) 180n + n-1nx

A car drove from a to B at the speed of 40km per hour. After 3 hours, it was forced to reduce 10km per hour due to rain. As a result, it arrived at B 45 minutes later than expected. The distance between a and B was calculated
The best answer is to write the equation and what is x!

The original plan is to arrive in X hours, then the distance between Party A and Party B is 40x:
40X=40*3+（40-10）*（X-3+3/4）
X = 5 and 1 / 4 hours
The distance between a and B is 40x = 210km

In the cuboid abcd-a1b1c1d1, it is known that ab = 4, ad = 3, Aa1 = 2, and the angle of AC1 and BD is obtained

Take point D as the origin, DA as the positive direction of X axis, DC as the positive direction of Y axis, dd1 as the positive direction of Z axis to establish the space rectangular coordinate system
So vector AC1 = (- 3,4,2), vector BD = (- 3, - 4,0)
|AC1 | * | BD | = 5 (radical 29)
Vector AC1 * vector BD = 9-16 = - 7
So the angle a between vector AC1 and BD satisfies
Cosa = - 7 / 5 (radical 29) = - 7 (radical 29) / 145
Because the angle range of straight line is [0,90 °]
So the value is π - arccos7 (radical 29) / 145

If a 2-3a + 1 = 0, find the value of a 4 + 1 / A
The fourth power of a & sup2; a

Do you mean 2 * a for A2 and 3 * a for 3A?
If yes, we can calculate a = 1; then 4 * a + 1 / a = 5;

Given two points a (0,4), B (8,2), and point P is a point on the X axis, what is the minimum value of PA + Pb? And the coordinates of P
Come on

Let AB: y = KX + B be a straight line
be
b=4
8k+b=2
∴k=-1/4
∴y=-1/4·x+4
When y = 0, x = 16
The minimum value of PA + Pb is ab = √ [(0-8) &# 178; + (4-2) &# 178;] = 2 √ 17

Simple calculation of 2 / 3 + (4 / 7 + 1 / 2) * 7 / 25

2/3+（4/7+1/2）×7/25
=2/3+（8/14+7/14）×7/25
=2/3+15/14 × 7/25
=2/3+3/10
=20/30+9/30
=29/30

If the circumference of the bottom surface of a cone is 4 π cm and the generatrix length is 5 cm, then the side area of the cone is 4 π cm______ ．

The side area of the cone is 12 × 4 π × 5 = 10 π (square centimeter)

There are eight numbers, six of which are 0.51 2 / 3 5 / 9 0.51 24 / 47 13 / 25. If the fourth number is 0.51 in descending order, what is the seventh one?
The seventh, not the fourth

2/3=0.6666.
5/9 =0.5555...
24/47 =0.5106...
13/25=0.52
51 2 / 3 5 / 9 0.51 24 / 47 13 / 25 in descending order:
0.51 0.51 24/47 13/25 5/9 2/3
The fourth is 0.51, then the other two numbers

Through the point P (2,0) to the circle x + y-2y-3 = 0, the tangent line is introduced, and the tangent equation is solved?

X & # 178; + Y & # 178; - 2y-3 = 0
x²+(y-1)² = 4
Center C (0,1), radius r = 2
① The slope does not exist, x = 2
② Let K exist
y=k(x-2)
d=|1+2k|/√(k^2+1)=r=2
|1+2k|=2√(k^2+1)
4k^2+4k+1=4k^2+4
k=3/4
y=3/4x-3/2
That is, 3x-4y-6 = 0

A car drove from a to B at the speed of 40km per hour. After 3 hours, it was forced to reduce 10km per hour due to rain. As a result, it arrived at B 45 minutes later than expected. The distance between a and B was calculated The best answer is to write the equation and what is x!

In the cuboid abcd-a1b1c1d1, it is known that ab = 4, ad = 3, Aa1 = 2, and the angle of AC1 and BD is obtained

If a 2-3a + 1 = 0, find the value of a 4 + 1 / A The fourth power of a & sup2; a

Given two points a (0,4), B (8,2), and point P is a point on the X axis, what is the minimum value of PA + Pb? And the coordinates of P Come on