Please solve math problems! Urgent!

1) Proof: This question is simple and only analyzes. Because FB=FC, and FB is parallel to AD, BF is the median line, the proportion of parallel lines in the triangle, it is easy to get BE=BA, it can be seen that the area of the triangle ABF and the triangle EBF is equal (equal height), and the same reason can obtain the area of the triangle EBF and the triangle FEC, etc., which are replaced by the same amount, and this problem is proved.

2) Prov: If the distance of the point F from the point B is X, then FC=A-X, then according to the graph, the triangle EBF is shared by the triangle AEF and the triangle BEC. The area of the triangle ABF (B+BE)XSIN 2,Be (BE+B)=X A is solved to obtain BE=XB (A-X), and the area of the triangle ABF is ABXSIN 2(A-X); The area of the triangle ebc beasin 2=bxasin 2(a-x), obviously the final result is the same, so it has nothing to do with the specific distance from the moving point f to the point b, therefore, the area of the two related triangles in the title is always equal.

1) Because F is the midpoint of BC, so BF=FC=, and BF AD, so BF is the median line of EAD, AB=BE, ABF and BEF are equal in height, and EFC is equal to BEF, equal bottom, equal area according to equal height of equal bottom, we can get: S ABF=S EFC.

2) Equal. Let bf=c, be=kab (because of the proportional relationship), then s abf=, s efc=, if the two are equal, i.e., simplified to a=(1+1 k)c, and this relationship holds, e.g., k=1 is the answer to (1).

Step 1: The sum of the four lines minus the sum of these eight numbers is equal to the sum of the four numbers of the horns.

Step 2: Among these eight numbers, the sum is equal to 24, only 8 + 7 + 6 + 3 and 8 + 7 + 5 + 4 and because 8 + 7 = 15, 8 and 7 can not be placed on a line, only diagonally! And because 8 + 4 = 7 + 5 = 12, they all have to add 2 to equal 15 and the number 3 is reused, so the four diagonal numbers can only choose 8 7 6 3

The last step: fill in the four numbers in the early corners of the four entangles (8 and 7 are placed at opposite corners), calculate the middle number and solve it.

Please send "this math problem" so that netizens can translate it for you. Thank you for your cooperation!

1. First empty: 3/5 multiplied by 3/5 equals 9/25.

Second empty: 1-9/25 left = 16/25.

2. The first time subtract 1/5, then 1/5 of 4 is the meter, the second subtraction is the remaining 1/5, then the 1/5 of the is is, subtract 2, then there is still the rice.

3. First empty: It takes 15 days for Team A to complete alone, so 1/15 of Team A is completed in one day; It takes 20 days for team B to complete alone, so A completes 1/20 in one day, so A and B can complete 1/15 + 1/20 = 7/60 in one day.

The second space: indicates how much A and B can complete the project together in five days.

The third blank indicates how many days it takes for A and B to work together to complete half of the project.

4. You should choose the answer 10/11.

Salt is 10 grams and water is 100 grams, then salt water is salt + water = 110 grams. Then the water should be 100 of the salt water divided by 110

Let the distance from A to B be s, the original velocity is v, and the original time is t.

s/4/v+(s-4)/

s=vt can be obtained with the above three formulas.

s = 756 73 km.

t = hours. v = 216 73 km h.

Let the distance between AB and the two places be s, and the original speed of the car is v

then s s-4).

Then the equation is solved.

I don't know where to ask!

The first line of rules.

Rule: -[n times of 2) multiplied by n times of (-1)] The law of the second line; -[n times of 2) multiplied by n times within (-1)] + 2 The law of the third row capacity: 1 2 times -[(n times of 2) multiplied by n times of (-1)] So the first question, n = 8, is substituted to get -254.

The second question is to add the above three laws, when the value is 1282, the value of n, and the solution is n=9, so these three numbers are 512, 514, 256 respectively.

Did you go high school or junior high school? Do you understand......