Find the maximum and minimum value of the function y = 8 + 2x-x ^ 2 in the interval [- 1,2]

Find the maximum and minimum value of the function y = 8 + 2x-x ^ 2 in the interval [- 1,2]

From y = - x ^ 2 + 2x + 8, the derivative of the function is y = - 2x + 2,
Let y = 0, the solution is: x = 1
When x = 1, substituting into the function, y = 9
Similarly, when x = - 1, y = 5
When x = 2, y = 8
So the maximum value of this function is 9 and the minimum value is 5

Answers to the first year's mathematics exercise book page 9 to 10
Mathematics learning guide book
Innovation exercise book

4555

3,6,10,15,21,28,36?

a2-a1=3
a3-a2=4
……
an-a(n-1)=(n+1)
Add
an-a1=3+4+…… +(n+1)=(n+4)(n-2)/2=(n²+2n-8)/2
So an = (n & # 178; + 2n-2) / 2

The diameter of a hair is about 0.06 mm = () nm, so 1 nm is equivalent to a fraction of the diameter of a hair
Those who can use scientific and technological methods should use scientific and technological methods

The diameter of a hair is about 0.06 mm = (60 μ m) = 60000 nm = 6 * 10 ^ 4 nm. 1 nm is equivalent to one 60000 th of the diameter of a hair

The travel problem of first order equation with one variable
A bus is 200 meters long, and a truck is 280 meters long. They are running in parallel tracks. After 16 seconds, the speed ratio of the bus to the truck is known to be 3:2. How many meters are the two cars running each other per second?

If the bus speed is set at 3xm / s, the truck speed is set at 2XM / s
16*(3X+2X)=200+280
80X=480
X=6
Bus speed = 3 * 6 = 18 m / S
Truck speed = 2 * 6 = 12m / S

For a job, Party A and Party B cooperate for 4 hours, and Party B and Party C cooperate for 5 hours. Now, after Party A and Party C cooperate for 2 hours, the remaining Party B needs 6 hours to complete, and how many hours does it take for Party B

It can be considered as follows: take the whole workload as 1, suppose that it takes x hours, y hours and Z hours for a, B and C to complete the work separately, then 1 / x, Y / 1 and 1 / Z of the workload can be completed by a, B and C per hour
So we have (1 / x + 1 / y) 4 = 1
（1/y+1/z)5=1
（1/x+1/z)5+(1/y)6=1
From these three equations, we can find the value of XYZ

3.2 L = () ml = () cubic decimeter

3.2 L = (3200) ml = (3.2) cubic decimeter

Grammar of English unit 5

If sb do(does) sth ,sb will do(be) ...

Ten red balls, nine white balls, eight yellow balls and two basketball balls are mixed and put into a bag. At least how many balls can be found at a time to ensure that four balls are of the same color

12 Oh pro ~ the following is the idea ~ consider the worst case of luck: the first touch four balls, are different colors. At this time, there are still nine red balls, eight white balls, seven yellow balls, one blue ball. You have one red, one white, one yellow and one blue ball in your hand. The second touch four balls, are all different colors. At this time, there are still eight red balls, seven white balls, six yellow balls

How many square meters is the area of one mu

About 100 square meters