1, solve the equation: 180-α-290-α= () 1? 180, and then α3
2. Use 10% and 5% brine to synthesize 10kg of 8% brine. /kloc-how many kilograms of 0/0% and 5% salt water are needed?
3. Suppose that the solution of 5x +2k =3 is a positive number, and the value range of k is
4.(2) If x -2a? If the solution of 1 is x > 3, then the value range of a.
? 2(x + 1)？ 1 1-x
(3) If 2x -a? The solution of 1 is-1 < x < 1, then (a+ 1)(b-2)= 1
? x -2b？ three
(4) If the solution set of 2x < a is x < 2, then a=
(5) If 2x -m ≤0 has a solution, the value range of m.
? 4x + 16？ 0
5. Given 3x +2y =m+1, and x > y, the value range of m; 2x +y =m - 1？
6. Assuming the uphill speed is 600m/h and the up-and-down speed is 400m/h, what is the average up-and-down speed?
7. Given 4(x +y -3) +x -y =0, then,; 2
? 3x +5y +3z =08, known? (z ≠0), then x :z =, y: z =; 3x -5y -8z =0？
9. When m=, the values of X and Y in the equation x +2y =6 are equal, and the values of X and Y are equal.
? 2x -y =3m - 10
10, given that point P(5a-7, -6a-2) is on the bisector of two or four quadrants, then a=.
? The solution of x+2y = 3m1211is 3x +2y =34. Find me. m？ x -y =9m
12. If the solution of equation 3m (x+1)+1= m (3-x)-5x is negative, then the range of m is.
13. The ship starts from point A, travels 200km northwest to 60 at point B, then travels 500km southeast from point B to 20 at point C, and then ∠ABC=.
14, 3x +5y =a +2, and the sum of x and y is 0, then a=.
? 2x +3y =a
1
15, a and b are antonyms and neither is 0, and c and d are reciprocal, so (a +b)? 5+
A and b are opposite numbers and both are not 0, so (a +b-1)? (b 2-cd =. A 3a+1) = .b
A and B are reciprocal, and C and D are reciprocal. If x =2, then 10a+10b +cdx =.
16, if m
M (fill in ">", "
4n 17。 If m +5 and (n -2) are reciprocal, then m =
18, there are 23 people working in A, and there are 17 people working in B. Now 20 people have switched to support, so the people working in A work in B.
Twice the number of people, how many people will Party A and Party B transfer?
00 19 as shown in the figure, it is known that in isosceles Rt △OAB, ∠ AOB = 90, and in isosceles Rt △EOF, ∠ EOF = 90, connecting AE and BF. Verification:
( 1)AE = BF； (2) AE⊥BF.
20. As shown in the figure, it is known that the quadrilateral ABCD is a square, e is the midpoint of AD, f is a point on the extension line of BA, and AF= 1AB, 2.
Known △ Abe△ ADF.
In the (1) diagram, which method can be used to change △ABE into △ADF? (3 points)
(2) What is the relationship between the line segment BE and DF? Prove your conclusion. (10 point) c
2