The distance between a and B is 300 km. The truck and bus leave from a and B at the same time. Four hours later, the two cars meet. It is known that the truck travels 35 km per hour. How many km per hour can the bus travel?

The distance between a and B is 300 km. The truck and bus leave from a and B at the same time. Four hours later, the two cars meet. It is known that the truck travels 35 km per hour. How many km per hour can the bus travel?

300 △ 4-35, = 75-35, = 40 (km), answer: bus travels 40 km per hour
{an} is an arithmetic sequence, BN = {1 / 2} ^ an, known B1 + B2 + B3 = 21 / 8, b1b2b3 = 1 / 8, (1) find an (2) find BN (3) find Sn = B1 + B2 + +bn
{an} is an arithmetic sequence, BN = {1 / 2} ^ an, known as B1 + B2 + B3 = 21 / 8, b1b2b3 = 1 / 8, (1) find an (2) find BN (3) find Sn (SN = B1 + B2 +) +bn)
B1b2b3 = (1 / 2) ^ (a1 + A2 + a3) = 1 / 8, so a1 + A2 + a3 = 3, let an tolerance be D, then 3a2 = 3, A2 = 1, B2 = 1 / 2bn / b (n-1) = (1 / 2) ^ [an-a (n-1)] = (1 / 2) ^ D, so BN is the proportional sequence B1 + B3 = 17 / 8, b1b3 = 1 / 4, so B1 = 2, B3 = 1 / 8 or B1 = 1 / 8, B3 = 2B1 = (1 / 2) ^ A1, so A1 = - 1 or A1 = 3
Hello
b1b2b3=(1/2)^(a1+a2+a3)=1/8
So a1 + A2 + a3 = 3, let an tolerance be D, then 3a2 = 3, A2 = 1
b2=1/2
Let's go step by step, let's say, B 1 = B 1 / 8, B 1 = B 1 / 8,
Sn can also be obtained
Because b1b2b3 = 21 / 8, BN = {1 / 2} ^ an. So a1 + A2 + a3 = 3; {an} is an arithmetic sequence, A2 = 1, let D, then (1 / 2) &# 710; (1-D) + 1 / 2 + (1 / 2) &# 710; (1 + D) = 21 / 8; d = - 2, an = - 1 + (- 2) (n-1);
bn=={1/2}^(-2n+1)
B1 = 2; BN is an equal ratio sequence
Sn=2(1-(1/2)^n)/(1/2)
∵bn=(1/2)^an ∴b(n+1)/bn=(1/2)^[a(n+1)-an]
∵ {an} is an arithmetic sequence ∵ a (n + 1) - an = D = constant ∵ {BN} is an arithmetic sequence
∴b1+b2+b3=b1（1+q+q^2)=21/8 …… （1） b1b2b3=(b1q)^3=1/8 …… （2）
From the solution of (1) and (2), we can get: B1 = 2, d = 1 / 4 or B1 = 1 / 8, d = 4
Ψ BN = 2 *. Expansion
∵bn=(1/2)^an ∴b(n+1)/bn=(1/2)^[a(n+1)-an]
∵ {an} is an arithmetic sequence ∵ a (n + 1) - an = D = constant ∵ {BN} is an arithmetic sequence
∴b1+b2+b3=b1（1+q+q^2)=21/8 …… （1） b1b2b3=(b1q)^3=1/8 …… （2）
From the solution of (1) and (2), we can get: B1 = 2, d = 1 / 4 or B1 = 1 / 8, d = 4
Ψ BN = 2 * (1 / 4) ^ (n-1) or BN = 1 / 8 * 4 ^ (n-1)
∵bn=(1/2)^an ∴an=-log2bn
∴an=-log2[2*(1/4)^(n-1)]=-1+2(n-1)=2n-3
Or an = - log2 [1 / 8 * 4 ^ (n-1)] = 3-2 (n-1) = - 2n + 5
1. 80% of a number minus 4.8 is equal to 3.2. Find this number. 2. A number minus one fifth of it is 4. What is three tenths of this number?
There are 72 roses in the garden, one eighth more than chrysanthemums, and orchids one third less than roses. How many orchids? How many chrysanthemums?
After cutting a cube with an edge length of 4 decimeters from a cuboid, the volume of the remaining cuboid is 42 cubic decimeters. What is the volume of the original cuboid?
Uncle Wang's orchard harvested 11250 kg of fruit last year, 8% more than that of last year. How many kg of fruit are harvested this year?
A pile of coal burned a quarter of it in November and two ninths of it in December. How many five twelfth tons was it in November compared with December? How many tons is this pile of coal?
1.10（3.2+4.8=8 8/80%=10）
5 【4/(4/5)=5】
2. Chrysanthemum = 72 / (9 / 8) = 8, orchid = 72 * 2 / 3 = 48
3.106 (cube volume = 4 * 4 * 4 = 64, original cuboid volume = 64 + 42 = 106)
4.12150 【11250*（1+8%）】
15 tons of coal, X / 4 tons in November and 2x / 9 tons in December
X/4-2X/9=5/12 X=15
It takes 8 days for a car to go from place a to place B, and 12 days for a truck to go from place B to place a
How many days
1 / (1 / 8 + 1 / 12) = 1 / (3 / 24 + 2 / 24) = 24 / 5 = 4.8 days
Let {an} be an arithmetic sequence, BN = (12) an. It is known that B1 + B2 + B3 = 218, b1b2b3 = 18. Find the general term an of arithmetic sequence
Let the tolerance of arithmetic sequence {an} be D, then an = a1 + (n-1) d.. BN = (12) a1 + (n-1) db1b3 = (12) A1 · (12) a1 + 2D = (12) 2 (a1 + D) = B22. From b1b2b3 = 18, B23 = 18, B2 = 12. Substituting the known condition b1b2b3 = 18b1 + B2 + B3 = 218, b1b3 = 14b1 + B3 = 178
One fourth of the sum of a number and two minus one sixth of the difference between two times and three equals one
De bracket... De denominator
these ones here...
(x+2)*1/4-(2x-3)*1/6=1
3(x+2)-2(2x-3)=12
X=0
Zero
The answer is 0
The distance between a and B is 720 km. A car and a freight car start from a and B at the same time
If the speed of the car is 1.25 times that of the truck, the two cars will meet after 4 hours. What are the speeds of the two cars? I'm waiting. Equations to be listed
Truck: 720 / 4 / (1.25 + 1) = 80
Car: 80 * 1.25 = 100
(LG2) (Log1 / 2 (1 / 4)) ^ - 1 + (log root 3 (2)) ^ - 1)
log(1/4)=2,
log2=1/log√3,
The original formula = (LG2 + log3) / 2
If the sum of half of a number and 4 is equal to one-third of the number minus 2, then the number is zero
Let this number be x, then:
1/2 x +4=1/3 x -2
The solution of the equation is x = - 36
Let this number be X
Two thirds x + 4 = three thirds X-2
The solution is x = - 36
It takes 8 hours for a car to go from place a to place B, and 12 hours for a truck to go from place B to place A. now they start from both places at the same time. When will they meet?
emergency
1 / (1 / 8 + 1 / 12) = 24 / 5 hours