When asking math problems, you need to use equations to solve them, and you need processes

Solution: If the husband is now x years old, then the wife is now (x-3) years old, and four years ago the husband was (x-4) years old and the wife was (x-7) years old.

Because 73-58 = 15 16, the son was not born four years ago.

So four years ago, the daughter was 58-(x-4)-(x-7)=(69-2x) years old, and this year the daughter is 69-2x+4=(73-2x) years old. Because the daughter is 2 years older than the son, the son is 73-2x-2 = (71-2x) years old this year.

According to the above analysis, it can be seen that x+(x-3)+(73-2x)+(71-2x)=73 is solved to obtain x=34

So this year the husband is 34 years old, the wife is 31 years old, the daughter is 5 years old, and the son is 3 years old.

Solution: 73-58=15 (years).

Because if each person adds 4 years in four years, it should be 4 4 = 16 years, and the addition of 15 years in the question means that the son was born 3 years ago.

So now my son is 3 years old.

Because my daughter is 2 years older than my son, my daughter is now 5 years old.

If the wife's age is x years, the husband's age is x+3 years.

So x+(x+3)+3+5=73

So 2x=62

So x = 31 (years).

So the wife is 31 years old, and the husband is 31 + 3 = 34 years old.

A: The wife is 31 years old, the husband is 34 years old, the daughter is 5 years old, and the son is 3 years old.

This is an increase of 73-58=15 compared to the age of four years ago

So the youngest member (the son) was not born 4 years ago and is now 3 years old.

The daughter is 3 + 2 = 5 years old.

The sum of the ages of the couple is 73-3-5=65

Let the wife's age be x

x+x+3=65

x=31, then the husband is 31+3=34 years old.

His wife is 31 years old.

My daughter is 5 years old. My son is 3 years old.

Four years ago, each of the four people was four years younger, a total of 16 years younger, so the son was 3 years old, and the daughter was 5 years old before he was born four years ago.

Let Dad be x years old, then x+x-3+5+3=73, and find ,,x=34, then Dad 34 and Mom 31

Let the wife x and the son y, then 2x+3+2y+2=73;i.e. x+y=34.

73-4*4=57, 58-57=1, so y=4-1=3, x=31.

So the husband is 34, the wife is 31, the daughter is 5, and the son is 3.

Four years ago, each of the four people was four years younger, a total of 16 years younger, so the son was 3 years old, and he was not born four years ago.

Answer: 34, 31, 5, 3

17.f(x) =1 2)sin(2x+ 6)minimum positive period t = monotonically increasing interval 2k - 2 2x+ 6 2k + 2

k - 4 x + 12 k + 4, k - 3 x k + 6, k is an integer.

2x+ 6 = 2k - 2 takes the minimum value -1 2, in this case, x = k - 3 , and k is an integer.

This seems to be a question in Huanggang in 2012:

Analysis] (1) The problem can be solved by listing a one-dimensional equation according to the meaning of the problem; (2) For the range of the value of the quantity x purchased at one time, the functional relationship between y and x should be determined in three segments, that is, the result is a piecewise function. (3) According to the three-stage function obtained in (2), under the condition of ensuring that "y should increase with the increase of x", determine the "x value range" that the larger the purchase quantity and the greater the profit, but the lower the **, and finally solve the problem.

Answer] Solution: (1) When the merchant buys x pieces of the product at a time, the sales unit price is exactly 2600 yuan, and the solution is 3000-10 (x-10) = 2600, and the solution is x = 50 Answer: When the merchant buys 50 pieces of the product at a time, the sales unit price is exactly 2600 yuan.

2) When 0 x 10, y=(3000-2400)x=600x;

When 10 x 50, y=x=-10x2+700x;

When x 50, y=(2600-2400)x=200x;

3) Because the more quantity to be satisfied with a purchase, the greater the profit obtained, so y should increase with the increase of x.

Y=600x and Y=200x both increase with the increase of x. y=-10x2+700x=-10(x-35)2+12250, when 10 therefore satisfies x, the value range should beThat is, when the quantity purchased at one time is 35 pieces, the unit price of the sale is exactly the lowest unit price.

Can you receive**,Too lazy to type,

At this time, the water has 10 (3+1) 3 = liters, and the alcohol liters.

Solution: Set the first time to pour out pure alcohol x liters.

Then after the first time there is alcohol 10-x, water x

Then pour out the mixture of X alcohol with state void water.

Poured out all of the x 10

So pour out the alcohol (10-x) x 10

List the vertical combustion equation 10-x-(10-x) x 10=10-x-x+x 10=

100-20x+x²=25

x-10)²=25

Solution: x=5 or 15 (rounded).

So for the first time pour 5 liters of pure alcohol.

If you have any doubts, you can pick hi