An object begins to slide on the ice surface at a speed of 10m / s, and decelerates evenly. After sliding for 10m, the object stops, so it takes a lot of time for the object to slide for 6m______ S (root is allowed)

∵S=12vt∴t=2SV=2s，a=vt=102=5m/s2∵S=at22∴t=2×65=10−2105．

Junior high school mathematics problem, one variable quadratic equation drop
1. According to statistics, a community owned 64 family cars at the end of 2006, and the number of family cars reached 100 at the end of 2008. (1) if the growth rate of family car ownership in the community from the end of 2006 to the end of 2009 is the same, how many cars will the community reach by the end of 2009? (2) the community decided to invest 150000 yuan in the construction of several parking spaces, and the construction cost is 5000 yuan per indoor parking space, It is planned that the number of outdoor parking spaces will not be less than twice that of indoor parking spaces, but not more than three times that of indoor parking spaces. How many two kinds of parking spaces can be built in the community? Please write down all possible schemes. (it's better to have a process) 2. A computer virus spreads very fast. If a computer is infected, it will be very difficult to find a solution, After two rounds of infection, 81 computers will be infected. (1) please use the knowledge you have learned to analyze how many computers will be infected by a computer in each round of infection? (2) if the virus is not effectively controlled, more than 50000 computers will be infected after several rounds of infection? (it is better to have a process)

The growth rate is (100 / 64) * * (1 / 2) - 1 = 25%. At the end of 2009, there are 100 * (1 + 25%) = 125 vehicles with X indoor parking spaces. When the total number of parking spaces is up to 5000x + 1000 * (2.5x) = 150000x = 20, a total of 20 indoor parking spaces and 50 outdoor parking spaces will be built. Another plan is to build 21 indoor parking spaces and 45 outdoor parking spaces, Only k = 0,1 in each round of infection, an average computer will infect a computer, then there will be a computer infected after the first round, and there will be so many computers infected in the second round, that is, a computer a = 81, so a = 9. ① in each round of infection, an average computer will infect 9 computers. If the number of machines infected in n rounds is y, then y = 729, when y = 9 ^ n = 3, ② there will be more than 700 computers, and ③ when 9 ^ n > 50000 n = 4, When y = 6561, n = 5, y = 59049, that is, after five rounds of infection, more than 50000 computers were infected
Thank you!

It is known that the equation x2 + (A-3) x + 3 = 0 has a constant solution in the range of real number, and there is just one solution greater than 1 and less than 2, and the value range of a is______ ．

Let f (x) = x2 + (A-3) x + 3, the problem is equivalent to that f (x) has a zero point in (1,2) according to the distribution of roots of quadratic equation, which is equivalent to If [1 + (a-3-3) 2 [4 + (a-3-3) 2 + 3] or [1 + (a-3-3) (a-3-3) 2 [4 + (a-3-3) 2 + 3] < 0 or [1 + (a-3-3-3) + [1 + (a-3-3) + [1 + (a-3-3) - 3] [(4 + (a-3-3) 2 (4 + (A-3) 2 (2) < 0 or (f (a + 1) [(a-1-1-12 or a-1-1 or A-1 or a-12-1 or a-12-12-1 or a-12-12-12-12-12, when △ 0, that is b2-4ac ≥ 0, that is b2-4ac ≥ 0, b2-4ac ≥ 0, b2-4ac ≥ 0, [(a-4-4-4-4-4-4ac ≥ 0, [(a-3-3-3-< a ≤ -So the answer is: - 1 < a ≤ - 23 + 3

1. 2 / 3x ^ 2 + 1 / 3x-2 = 2 / 3 (x -) ^ 2 +
2. If the quadratic trinomial x ^ 2 + 4x + k about X is a complete square expression, find the value of K
Q: how many values of K are there? One

2/3X^2+1/3X-2
=2/3(X^2+1/2X)-2
=2/3(X^2+1/2X+1/16-1/16)-2
=2/3(X+1/4)^2-(2/3)*(1/16)-2
=2/3(X+1/4)^2+(-49/24)
=2/3[X-(-1/4)]^2+(-49/24)
X^2+4X+k
=X^2+2*2*X+2^2-2^2+K
=(X-2)^2+(K-4)
Is a complete square, then K-4 = 0
K=4

We know the quadratic equation MX2 - (2m-1) x + m-2 = 0 (M > 0) about X. (1) prove that the equation has two unequal real roots; (2) if the two real roots of the equation are x1, X2 respectively, and (x1-3) (x2-3) = 5m, find the value of M

(1) The discriminant △ = (2m-1) 2-4m (m-2) = 4m2-4m + 1-4m2 + 8m = 4m + 1 ∵ m ∵ 0 ∵ 4m + 1 ∵ 0, so the equation has two unequal real roots. (2) according to Weida's theorem, X1 + x2 = 2m − 1mx1x2 = m − 2m, so (x1-3) (x2-3) = 5mx1x2-3 (x1 + x2) + 9 = 5mm − 2m-3 × 2m − 1m + 9 = 5

Solving practical problems with linear equation of one variable (travel problem)
Li Bin plans to travel from home to Zhuque mountain by bike. When he sets out, he thinks that if he rides at the speed of 8 kilometers per hour, he can arrive at 12 noon; if he rides at the speed of 12 kilometers per hour, he can arrive at 10 o'clock; but it's better not to be fast or slow, and it's just 11 o'clock. So, what's his best driving speed?
The solution of a linear equation with one variable is given,

Let's set out at Libin's x-point
8(12-x)=12(10-x)
X = 6 points
Distance: 8 (12-6) = 48 km
48 / (11-6) = 9.6 km / h
The speed is 9.6 km / h

Solving linear equation with one variable
It takes five hours for an express train to go from place a to place B, and 0.2 hours more for a local train to go from place B to place a than the express train. The two trains leave from both places at the same time. Two hours later, the local train stops at a station, and the express train continues to run for 96 kilometers to meet the local train. Q: how many kilometers are there between the two places?
Let's be clear. Let's give high marks

Let s be the distance between Party A and Party B. this problem first calculates that the express train takes 5x1 / 5 = 1 hour, because it started for 2 hours at the same time, so the express train has gone back and forth, and returned to Party B, and started again. The local train only drove 2S / 5 and stopped. When the express train came, it just finished the 3S / 5 which the local train was going to take, and told the degree of the road is 96 km, so 3S / 5 = 96 km, and S = 160 km
It's already very detailed

It takes 20 seconds for a train to run at a constant speed through a 300m long tunnel. There is a light on the top of the tunnel, which lights vertically downward. If the light shines on the train for 10 seconds, then the speed of the train is______ ．

Let the length of the train be x, from the meaning of the question: 300 + X20 = X10, the solution is: x = 300, then the speed of the train is 300 △ 10 = 30m / s. answer: the speed of the train is 30m / s. so the answer is: 30m / s

There is a linear equation with one variable to solve the travel problem
A marching column moves at the speed of 8 km / h, and the correspondent at the end of the column rushes to the front of the column at the speed of 12 km / h to deliver a document. After the document is delivered, it immediately returns to the end of the column, which takes 14.4 minutes

Suppose the team length is X
x/(12-8)+/(8+12)=14.4/60
x/4+x/20=0.24
6x=4.8
X = 0.8 km
Here's the theory of relativity. Look at it for yourself

On the solution of travel problem with linear equation of one variable
Party A and Party B go from place a to place B. Party A walks for 2 hours before Party B starts. As a result, Party B is 15 minutes late than Party A. It is known that the speed of Party A is 4 km / h and that of Party B is 6 km / h. how to calculate the distance between two places? Let's set the distance between two places as X

x/4-2=x/6+0.25

An object begins to slide on the ice surface at a speed of 10m / s, and decelerates evenly. After sliding for 10m, the object stops, so it takes a lot of time for the object to slide for 6m______ S (root is allowed)