Mathematics engineering problems in Junior Three For a project, team a will complete it in 40 days. If team B will complete it in 30 days, team a and team B will cooperate for another 20 days 1: How many days does it take for engineering team B to do it alone? 2: The project team is divided into two parts, one part of which takes X days, the other part takes y days, where x and y are the whole tree, and X and y are the whole tree

Mathematics engineering problems in Junior Three For a project, team a will complete it in 40 days. If team B will complete it in 30 days, team a and team B will cooperate for another 20 days 1: How many days does it take for engineering team B to do it alone? 2: The project team is divided into two parts, one part of which takes X days, the other part takes y days, where x and y are the whole tree, and X and y are the whole tree

The velocity of a is 1 / 40, the velocity of B is (1-1 / 40x20) / 50 = 1 / 100
That is, B alone to complete 100 days
1/40X+1/100Y=1
Y = 100-2.5x12, and X is even
So 12

Engineering problems in solving mathematics problems in grade three of junior high school
In the process of road reform, a 1000m long pipeline needs to be built by Party A and Party B. Party A needs to build 70m pipeline every day, and Party B needs to build 50m pipeline every day. If the project is required to be completed within 10 days, there are several plans? The process and results should be more detailed
We need it now

A shop 10 days is 700 meters, 300 meters left, so B Shop 6 days, that is, in 10 days, a dry 10 days, B dry 6 days; according to this: a dry 9 days, 630 meters, 370 meters, B dry 7.4 days, a dry 8 days, 560 meters, 440 meters, B dry 8.8 days, a dry 7 days, 490 meters, 510 meters, B dry 10.2 days, the same: B dry 10 days, 50

The trial sale of a kind of clothing with a cost of 100 yuan per piece in a shopping mall stipulates that the unit price of sales during the trial sale period shall not be lower than the unit price of cost, and the profit shall not be higher than 40%. After the trial sale, it is found that the sales volume y (pieces) and the unit price x (yuan) conform to the linear function y = KX + B, and when x = 120, y = 80; when x = 125, y = 75
(1) Find the expression of the first-order function y = KX + B;
(2) If the profit of the shopping mall is w yuan, try to write the relationship between the profit W and the sales unit price X; when the sales unit price is set at how much yuan, the shopping mall can get the maximum profit, and what is the maximum profit?
(3) If the profit of the store is not less than 2275 yuan, try to determine the range of sales unit price X

(1) From the problem meaning: 80 = 120K + B; 75 = 125k + B solution: k = - 1, B = 200, then the expression of the linear function y = KX + B is y = - x + 200 (2) w = (X-100)? (- x + 200) = - x ^ 2 + 300x-20000 = - (X-150) ^ 2 + 2500, (4 points) ∵ the opening of the parabola is downward, ∵ when x < 150, w increases with the increase of X

Given 12a & # 178; + 7b & # 178; + 5C & # 178; ≤ 12a | B | - 4B | C | - 16c-16, find the values of a, B and C

12a² + 7b² + 5c² ≤ 12a|b| - 4b|c| - 16c - 1612a² + 7b² + 5c² - 12a|b| + 4b|c| + 16c + 16 ≤ 0(12a² - 12a|b| + 3b²) + (4b² + 4b|c| + c²) + (4c² +...

If 6A = 8b, then a: B=______ ．

If 6A = 8b, then a: B = 8:6

If 6A = 8b, then a: B=______ ．

If 6A = 8b, then a: B = 8:6

6A = 8b, then a: B = 3:4______ (judge right or wrong)

If 6A = 8b, then a: B = 8:6 = 4:3

A ^ + B ^ - 6a-8b + 25 = 0, B / A-A / b

a^+b^-6a-8b+25=0
a^-6a+9+b^-8b+16=0
(a-3)^+(b-4)^=0
Since the addends are all nonnegative, now and are 0, then they are all 0
So:
a-3=0
b-4=0
a=3
b=4
b/a-a/b=4/3-3/4=7/12

(5b + 3a-5c power) - (12b + 7a + C Power)

(the power of 5B + 3a-5c) - (the power of 12B + 7a + C)
=The power of 5B + 3a-5c the power of 12b-7a-c
=-The second power of 7b-4a-6c

(- 4 / 7a ^ 4B ^ 6C ^ 5) ^ 3 + (- 3. / 7a ^ 3B ^ 5C ^ 4) ^ 3 * (ABC) ^ 3 calculation

(-4/7a^4b^6c^5)^3+(-3/7a^3b^5c^4)^3*(abc)^3
=-64/343a^12b^18c^15-(3/7a^3b^5c^4*abc)^3
=-64/343a^12b^18c^15-27/343a^12b^18c^15
=-91/343a^12b^18c^15
=-13/49 a^12b^18c^15