Young pioneers went to plant trees. If each person digs five tree pits, there are still three tree pits that no one digs. If two of them dig four tree pits each and the others dig six tree pits each, they will have just dug all the tree pits. How many young pioneers are there in * *? * * * How many tree pits have been dug?
Answer and analysis:
This is a typical profit and loss problem, and the key is to unify the second sentence, "If two of them dig four tree pits each, and the rest dig six tree pits each, just dig all the tree pits". That is, six tree pits should be dug for each person to form a unified standard. That's equivalent to each person digging six tree pits, which means the difference is (6-4)*2=4 tree pits. So the total profit and loss is 3+4=7, so there are 7/(6-5)=7 young pioneers, and * * * has dug 5*7+3=38 pits.
The total profit and loss is equal to 3+(6-4)*2=7, there are 7/(6-5)=7 young pioneers, and * * * has dug 5*7+3=38 tree pits.
The topic says that this formula is always less than zero, so the maximum value of f(x) is < 0, but this sentence is not rigo