)
(1)
(2)
(3)
(4)
12, the following deformation is correct (
)
(1)
if
, then
(2)
if
, then
(3)
, then
(4)
if
, then
13 as shown on the right, in △ABC,
AB=8，AC=6，
AD is the center line of △ABC, then △ABD and △ADC
The difference between perimeters is (
)。
(1)
14
(2)
1
(3)
2
(4)
seven
14, if
Is a non-negative number, then
The value range of is (
)
(1)
(2)
(3)
(4)
15, equation
and
, then
The value of is (
)
(1)
five
(2)
six
(3)
seven
(4)
eight
16, inequality group
There is no solution in the solution set of, then
The value range of is (
)
(1)
(2)
(3)
(4)
9. If
b
, the following kinds of errors are (
)
Answer, answer
+
four
b
+
four
b、2
+
3a
2
+
3b
C and a
-
six
b
-
six
d、4
-
3a
four
-
3b
10. If P(m+3
M-5) is on the X axis, then the coordinate of point P is (
)
Answer, (-3,0)
(0，-3)
c 、( 8，0)
d 、( 5，0)
1 1. The distance from a point outside a straight line to this straight line is from this point to this straight line (
)
A
Vertical line segment
B,
vertical line
C, the length of the vertical section
D, the length of the vertical line
12. The following groups of line segments are edges that cannot form a triangle (
)
One, four, three, three.
1，5，6
c、2、5、4
d、5、8、4
27. It is known that the distance between A and B is 10 km. A goes from A to B, and B goes from B to A. At a certain moment, they are 2 kilometers apart. If their speeds are the same, then the distance between A and B is (
)
A
4 kilometers
B
6 km
C
7 kilometers
D
4 km or 6 km
28. With the three numbers of 2, 3 and 4, you can write an even number with three digits that are not repeated, and then add these numbers together, and the sum is (
)
A
1332
B
576
C
666
D
1998
29. There are some statements about the opposite number as follows:
① Rational numbers with opposite signs are opposite to each other.
② The numbers represented by two points on both sides of the origin are opposite.
③ Two different numbers with equal absolute values are opposite; ④ Two rational numbers represented by two points with equal distance from the origin are opposite. One of the correct statements is that
(
)
A
1
B
two
C
three
D
four
19. The distance between a and b is 20km. A and B drive in the same direction from A and B respectively, and meet in two hours. After meeting, A immediately returns to A, and B still moves towards A. When A returns to A, what are the speeds of B from A 2km, A and B respectively?
20. There are 70 workers in a workshop, each of whom processes 15 shafts or 12 bearings on average every day. How should the workers allocate so that the produced shaft and bearing can just match? (Only one shaft and two bearings can form a set)
2 1. 600g of 7% brine was prepared with two kinds of brine with concentrations of 8% and 5%. How many grams do you need for two kinds of brine?
22. A group of students from a certain grade went to the lecture hall. If there are 14 people in each row, there are 12 people.
People have no seats; If there are 16 students in each row, 8 more students can attend classes. How many students are there? How many rows of seats are there in the classroom?
23. in the equation y=ax2+bx+c, when x=2, y = 3；; When x= 1 and x=3, the values of y are equal; When x=0, the value of y is 5 larger than when x=- 1. Find the values of a, b and C.
24. A car is driving on the east-west expressway. Starting from a, heading east is positive. In one day, the driving records of cars are: +20km,-15km, +30km,-10km,-10km. Q:
( 1)
Will the car go back to a place when it stops driving? How many kilometers is it from a? Is it in the east or west of a place?
(2)
How many miles did the car travel on this day?
I bought 10 stamp, 20 stamps, 50 stamps and 50 stamps from 3 yuan *** 18 stamps. The total face value of 10 stamp is the same as that of 20 stamps. How many stamps did I buy each of these three stamps?