Please help me solve this problem, thanks!

C1=B1=1,C2=A1=2,S3=C1+C2+C3=13 4 then C3=13 4-1-2=1 4, i.e. B2=C3=1 4 Then the common ratio Q=B2 B1=(1 4) 1=1 4 So an=2+2(n-1)=2n,bn=b1*q(n-1)=(1 4) (n-1).

Assuming that the first 100 items contain n ans, then the number of bns is: 1+2+4+......2^(n-1)=2^n-1

So n+2 n-1 100, then n takes a maximum of 6, that is, an term containing 6 an, then an term containing 100-6=94 bn.

So s100=(2+4+6+......12)+[1+(1/4)^1+(1/4)^2+……1/4)^93]

43 and 1 3-3 (1 4) 93

b1=1 a1=2 b2=13 4-3=1 4 i.e. the common ratio is 1 4

a1=c2 a2=c5 a3=c10 then an=c(n 2+1), i.e. a10=c101

Then s100 s(a9)+s(b91) Then set the formula and add it to come out, I forgot the formula.

This student, the determination theorem of similar triangles is 1, the three corresponding sides are proportional to 2, the three corresponding angles are equal to 3, the two sides correspond to proportional, the angles are equal, 4, the two angles are equal, and the sandwich edges correspond to the proportions, I hope it will help you! Hope to adopt!

Both triangles are similar, see ** for details.

(1) Similarity, reason.

In two triangles, ab:ab =10:150=1:15bc:b c =12:180=1:15

ac:a′c′=15:225=1:15

ab:a′b′=bc:b′c′=ac:a′c′∴△abc∽△a′b′c′

2) Similarity, reason.

In two triangles, c= c = 90°

ac=18cm,ab=30cm

Get BC=24cm

a′c′=12cm, a′b′=20cm

Get b c = 16 cm

bc:b′c′=24:16=3:2，ac:a′c′=18:12=3:2

Whereas c= c =90°

abc∽△a′b′c′

（1）2：5

The similarity ratio of the area of two similar triangles is the square of the similarity ratio of their side lengths, so the similarity ratio of the area is the square of the side length, that is, 2:5

The circumference similarity ratio is equal to the side length similarity ratio, which is equal to the square of its area similarity ratio, so the area similarity ratio is 1:4

The larger area is 25 (4 5) = 20

ACD and BCD are similar triangles.

Let the cd edge be 1

Solve ad=3

So if the similarity ratio is ad:cd = 3:1 (sides of equal angular pairs), then the area ratio is 3:1

The answer has been given, as shown in the figure below, the content is detailed, if you are satisfied, please give it a thumbs up.

It's not easy to do the question, thank you!

Solution: Because decf is a square.

And the area is 36, so EC=6m, DE is parallel to AC, so the triangle DCE is a similar triangle to the triangle ABC, so be ed=bc ac, because be BC=2 5, so be ec=2 3, because EC=6, so BE=4, BC=EC+BE=10, so 4 6=10 AC, AC=15

Because decf is a square, the triangle abc is a right-angled triangle, so the area of the triangle acb = ac*cb 2=10*15 2=75

decf is a square.

afd=c=90°, ec=df=fc and a are common angles.

abc∽△adf

af/ac=df/bc=ec/bc=(bc-be)/bc=1-2/5=3/5

fc/ac=(ac-af)/ac=1-af/ac=1-3/5=2/5

ac=5/2·fc，bc=5/3·ec

The square area is 36, so EC de 6. And because be is 2 to 5 than bc, let be be x solvable be is equal to 4, and then according to the similarity solveable ac 15, the solvable area is 75

f(1) in 1999

After the award**f(1)=19800

f(2) in 2000

f(2)=f(1)*

f(3) in 2001

f(3) = 2 of f(1)*

To the power of 2002 it was f(4).

f(4) = 3 of f(1)*

power. f(x)=f(1)*

x-1 power.

f(10) in 2008

f(10) = 9 of f(1)*

Power = 19800 * after the prize **).

f(11) in 2009

Interest earned = f(10)*

16.29 million.

Therefore, the total amount of bonuses paid in 2009 was about 8.15 million.

21. It shows that the Song Dynasty was prosperous in China's overseas countries. **Encourage the outside world**; China's shipbuilding industry is developed, and the ship is equipped with a compass needle, which can sail to the ocean; The economic prosperity of the two Song Dynasty has provided a solid foundation for the prosperity of overseas countries.

Unrelieved (馁): No courage to be cured (healed): The illness is cured.

Nightfall (Coming): Coming, Coming Far in the Sky (End): Margin.

Bo) ancient and modern: know a lot (if) nothing: like.

Intimacy (between): gaps in the country (Thailand) and people's peace: peace, stability.

The sound of the wind is whirring, and the sound of the rain is rustling

Since two systems of equations have the same solution, you can combine the above equations from the two systems of equations into a single system of equations. Substituting x=2y+5 into 5x+y=3 to get y=-2 11, then x=6 11. In this way, substituting the values of x and y into the lower part of the first equation system, we can find a=5 3;Then substitute the following to find b=41 2.