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A preliminary mathematical problem In solving the equations ax + by = C (1), ax by = - 3 (2), due to carelessness, Xiao Ming mistook - 3 in equation (2) as 3, and got the solution as x = 3, y = 6. Xiao Gang mistook the value of B in equation (1), and got the solution as x = 15, y = 18. It is known that neither of them made any other mistakes. Try to find the value of a, B, C
Let Xiaogang mistake the value of B in equation (1) for D, then
3a+6b=c (1)
3a-6b=3 ( 2)
15a+18d=c (3)
15a-18b=-3 ( 4)
The values of a, B and C can be obtained by solving the quaternion linear equations
A math problem, ha, ha, thank you!
An express train and a local train run opposite each other. The length of the express train is 200 meters, and that of the local train is 250 meters. The time for the passengers sitting on the local train to see the window where the express train has expired is 6 seconds. What is the time for the passengers sitting on the express train to see the window where the local train has expired?
The relative speed is the same
Walk 200 meters in 6 seconds
250 meter walking time 6 * 250 / 200 = 7.5 seconds
Compare the numbers of the following groups,
0001 and - 10000 - 5 / 7 and - 3 / 7 - 5 / 9 and - 5 / 7 - 4 / 7 and - 5 / 9
0.0001 is greater than - 10000; positive number is greater than negative number. - 5 / 7 is less than - 3 / 7; 5 / 7 is greater than 3 / 7, plus negative sign on both sides, on the contrary. - 4 / 7 is less than - 5 / 9, - 4 / 7 = 36 / 63, greater than 5 / 9 = 35 / 63, plus negative sign
RELATED INFORMATIONS
- 1. Compare the size of - 8 / 9 and - 7 / 9
- 2. Compare the sizes of 222221 / 222223 and 333331 / 333334
- 3. Compare size (1) Compare size ①1²＋5² ﹙﹚ 2×1×5 ②﹙－2﹚²＋3² ﹙﹚ 2×﹙－2﹚×3 ③（－4）²＋﹙－4﹚² ﹙﹚ 2×（－4﹚×（－4﹚ (2) Follow the example of ①, ② and ③ in (1) to write a formula respectively; (3) What regular conclusion do you find through observation, conjecture, exploration and induction? Please try to explain this regular conclusion
- 4. Three students have done a total of 20 math problems. If B does one more problem, it will be twice as many as a. if a does five less problems than C, how many math problems did each of the three students do
- 5. One day, a, B and C do math problems. It is known that a has done 6 more than B, and C has done 2 times as much as a, 22 more than B, so they have done all of them______ A math problem
- 6. Ask a math question about comparing size It is known that the quadratic function f (x) satisfies f (- x + 2) = f (- 2-x). Compare the sizes of F (negative half root sign 3), f (negative third π) and f (- 1)
- 7. Compare the size 10X3/8（ ）10 4X3/4（ ）4 3/8X10（ ）3/8 4/3X4（ ）4/3
- 8. What is the common multiple of 8 and 9 within 50?
- 9. 1 2 3 4 56 7 8 9 10 11 12 13 14 15.......... 96 97 98 99 100 a B 1. Frame out the four numbers C D from the middle 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 ............... 96 97 98 99 100 a b 1. Frame out the four numbers C and D, set the minimum number as X, and express the sum of the four numbers with integral a 2. Box out the five numbers B, C and D, and let the number in the middle be y, If their sum is equal to 85, write these five digits
- 10. 2/1+6/5—12/7+20/9—30/11+42/13—56/15
- 11. Let's do it for you, 1: For a project, if it is contracted by Party A and Party B and completed in 12 / 5 days, it needs to pay 180000 yuan; if it is contracted by Party B and Party C and completed in 15 / 4 days, it needs to pay 150000 yuan; if it is contracted by Party A and Party C and completed in 20 / 7, it needs to pay 160000 yuan. Now the project is contracted by a single team. On the premise that the project can be completed in one week, which team has less contract cost? 2: When a shopping mall sells a commodity, its profit margin increases by 8 percentage points because the purchase price is 6.4% lower than the original price. Then the original profit margin of this commodity is... (Note: profit margin = (sales price purchase price) X100%. I can't understand the first floor product.) (just these two questions, 50 points.) 3: The number of integer solutions (x, y) of the equation x & sup2; + XY + 2Y & sup2; = 29 is () A.2 B.3 C.4 D. infinite
- 12. 2*4/1+6*8/1+… +2006*2008/1+4*6/1+8*10/1+… What is 2004 * 2006 / 1
- 13. The solution set of inequality 2 Λ X - (3 / x) + 1 ≤ 1 / 2 is 2∧[x－﹙3／x﹚＋1]≤1／2
- 14. What is (x ^ n-1) ^ 2 (- 3 ^ 3) (- x ^ n) equal to?
- 15. Choose + - x division or bracket to write 1,2,7,9 into a formula, the result is 24, the formula is?
- 16. 1 2 3 4 5 6 7 8 9 10 = 2014 with addition, subtraction, multiplication, division of brackets, etc. without changing the numerical order, it is equal to 2014
- 17. Six out of seven / five out of nine * equals seven out of eight
- 18. The result of the addition and subtraction of four numbers is 24 3,4,-6,10, 3,-5,7,-13 Write three different calculation methods for each group of numbers
- 19. The sum of a two digit one digit number and a ten digit number is greater than 10. If 36 is added to the two digits, it is exactly equal to the two digits after the exchange of two digits, Find the original two-digit number, with one-dimensional inequality
- 20. Here is another symmetrical equation, but one of the numbers is not written out, and is replaced by a bracket: 12 × 46 () = () 64 × 21 () Here is another symmetrical equation, but one of the numbers is not written out and is replaced by a bracket: 12×46（）=（）64×21 What is the number of () in the formula? Can you work it out with the equation?