Bao Xiao and his parents are playing on the seesaw in the playground. His father weighs 72 kilograms and sits at one end of the seesaw. Bao Xiao, who weighs only half as much as his mother, sits at the other end of the seesaw with his mother. At this time, his father's feet were still on the ground. Later, Bao Xiao borrowed a pair of dumbbells weighing 6 kilograms and put them at the end where he sat with his mother. As a result, Bao Xiao and his mother escaped from danger. Guess how much Bao Xiao weighs? (accurate to 1 kg)
3. It is known that a factory has 70m and 52m fabrics. It is planned to produce 80 sets of A and B fashions with these two fabrics. It is known that the fabrics needed to make a set of A and B fashions are shown in the following table. Can the factory complete the task with existing raw materials? If yes, how many production plans are there? Please design it.
70 meters and 52 meters
A 0.6 m 0.9 m.
B 1. 1.4m
4. Transport a batch of goods by several cars with a load of seven tons. If each car only carries four tons, there is still 10 tons of goods left. If each car is full of seven tons, the last car will not be empty. Excuse me: How many cars are there?
It is known that Limin Garment Factory has 70m fabric A and 52m fabric B, and it is planned to produce 80 sets of M and N fashions with these two fabrics. It is known that making a set of M fashions requires 0.6 meters of fabric and 0.9 meters of fabric. To make an N-fashion, fabric A needs 1. 1 m, and fabric B needs 0.4m.. If the number of fashion sets for producing n models is x, there are several best schemes for producing these two models with this batch of fabrics: scheme: there are x rooms and y people.
There are 4x+20 = y... 1.
8x-8 & lt； y & lt8x......2
8x-8 < 4x+20 & lt； 8x
The solution is x = 6 and y = 44.
Answer: let Bao Xiao weigh x kilograms.
Then 2x+x
2x+x+6 & gt； Seventy two
22
So x=23.
Solution: Set a product X set and a product B set.
Then x+y=80.
0.6x+ 1. 1y & lt； =70
0.9x+0.4y & lt； =52
36
So x=36, 37, 38, 39, 40.
Therefore, tasks x=36 and y=44 can be completed; x=37，y = 43x=38，y = 42x=39，y = 4 1； x=40，y = 40
Solution: there are x cars and y tons of goods.
There are 4x+10 = y.
7x-7 & lt； y & lt7x
10/3 < = x & lt； = 17/3
So x = 4,5.
So there are four or five cars.
Solution: Set M Fashion X setting and N Fashion Y setting.
Then x+y=80.
0.6x+ 1. 1y & lt； =70
0.9x+0.4y & lt； =52
36
So x=36, 37, 38, 39, 40.
So x=36, y = 44x=37, y = 43x=38, y = 42x=39, y = 41; X=40, y=40 math synchronous exercises in the first day of junior high school.
I. Fill in the blanks:
(1) If x
(2) If |a+2|+(b+ 1)2=0, then (1/a)+b = _ _ _ _ _ _
(3) The divisor of 4080300 with three significant digits is _ _ _ _ _ _ _
(5) algebraic expressions a2, a2+ 1, (a+ 1)2, a2+|a|, _ _ _
(6)(-32) radix is _ _ _ _, power is _ _ _ _, and the result is _ _ _
(9) A three-digit number, where the ten digits are A, one digit is three times smaller than the ten digits, and the hundred digits are half of the ten digits. Algebraically, this three-digit number is _ _ _ _ _
(10) If the value of the polynomial (2mx2-x2+3x+1)-(5x2-4y2+3x) has nothing to do with x, the value of 2m3-[3m2+(4m-5)+m] is _ _.
Second, multiple-choice questions:
(1) known x
a、2 B、-2 C、+2 D、0
(3) If the square root of a rational number is equal to -x, then x is ()
A, negative b, positive c, non-negative d, non-positive.
(4) If the numbers represented by the numbers m and n on the number axis are as shown in the figure, then m, n, -M and -N are arranged in the order from small to large, which is ().
a、n & ltm & lt-n & lt； -m B、m & ltn & lt-m & lt； -n C、n & lt-m & lt； m & lt-n D、n & lt-n & lt； m & lt-m
5) If |a-3|=3-a, the value range of a is ().
a、a≥3 B、a≤3 C、a>3 D、a