Ask two math questions, ask two math questions

5.f(x) is an odd function.

f(0)=0

2^0+b=0,b=-1

then f(x)=2 x+2x-1

f(-1)=-f(1)=-(2^1+2*1-1)=-37.From the meaning of the title, we can see that the common ratio q<1, and q=1 2 n (n is a positive integer) then s=b1 (1-q)=1 7

7b1=1-q

and b1 = 1 2 m (m is a positive integer).

The requirement is only satisfied if q=1 8 and b1=1 8.

So the general formula is:

bn=b1*q (n-1)=1 8 n (n is a positive integer) satisfied, thank you

The fifth question (the answer seems to be different from yours, maybe I miscalculated, but the idea is correct) first finds b=-1 from f(0)=0

So f(x)=2 x+2x-1

And because f(x) is an odd function.

f(-1)=-f(1)=-3

Question 7. From the meaning of the title, {bn) is an infinitely decreasing proportional sequence (only an infinitely decreasing proportional sequence has an sum of terms).

The sum of terms of an infinitely decreasing proportional series is s=b1 (1-q)=1 7.........1) Let the first term be (1 2) m, then q=(1 2) m or more are brought into (1).

So m=3 so we get b1=1 8 q=1 8 so bn=1 8 n

Feel free to ask.

1.It should be that f(x) is an odd function, so f(0)=0,1+b=0,b=-1,f(x)=2 x+2x-1,f(-1)=-f(1)=-3 How is your answer -4?

1.After forging, the shape changes but the volume does not.

The volume of this ingot is cubic meters).

2 dm = m.

The length of the forged cuboid ingot is meters).

2.The area of each face of the cube is 96 6 = 16 (square centimeters) The edge length of the cube is 4 cm, so the height of the original cuboid is 4 + 6 = 10 cm.

It turns out that the volume of this cuboid is 16 10=160 (square centimeters).

Since the volume is equal before and after forging.

So length.

So length = 3 meters.

2) If the surface area is 96 square centimeters, and the side length of the cube is xcm, then 6x 2=96, so x=4cm

So it turned out to be 4cm long, 4cm wide, and 10cm high

The volume is 4 4 10=160cm

Question 1: Set the length of the high-speed rail to be x kilometers.

Equation 3 5x=1 2x+25

Solution: x=250

The high-speed rail is 250 kilometers long.

Question 2: There are 5x girls and 6x boys.

Equation 5x+5=8 9 6x

Solution: x=15

5x=75 female students, originally 75 people.

Hey, hey, take it!

1.The Shanghai-Hangzhou high-speed railway is about x kilometers long, 3 5) x = (1 2) x + 25

3x/5=x/2+25

x/10=25

x=2502.If the number of boys is x, then the number of girls is 5x 6 and the number of girls is 8x 9

5x/6+5=8x/9

8x/9-5x/6=5

x=905x/6=75

Answer to the first question.

$24 for the second question.

Answer: Soccer is 20 yuan more expensive than each basketball.

Football is $29 more expensive than each volleyball.

84x2/7=24

A pair of pants is 24 yuan cheaper than a blouse.

90x2 9=20, each soccer ball is 20 yuan more expensive than each basketball.

90x9/10=81

1.Pants** are 60 yuan, which is 24 yuan cheaper than a top.

2.Football is $110, volleyball is $81, and football is $29 more expensive than basketball.

1.Take out 1 from tank A and put it into tank B, at this time, the number of tails of goldfish in both tanks is equal, indicating that A is more than B: 2.

Take out 1 from tank B and put it into tank A, at this time, the number of goldfish in tank B is less than A: 2 + 1 * 2 = 4, B is 1 2

Then A is: 4 (1-1 2)=8

B is: 8-4=4, B is: 4+1=5, A is: 5+2=7.

Suppose last year A sold x pairs, then B sold 12200-x pairs.

x=6000

In the year, A and B each sold 6,000 pairs and 6,200 pairs of Liang Mu stoves.

Set up bamboo poles x meters long.

x+x=m.

The bamboo pole is long and the rope is 2 meters long.

1.Drying rate = original mass and remaining mass.

500g÷430g

Moisture content = 1 - drying rate.

2.There is no need to count the concentration ......

I used to have a glass of pure milk, but then I drank it all; I added half a glass of water twice, and I drank it all up; So a total of a glass of water, a glass of milk.

Problem 1: Drying rate = 430 500

Moisture content = 70 500

Question 2: As much as I added 2 times and a half cup of water.