The seventh grade equation calculation problem is urgent! 1, the known rational numbers x, y and z satisfy x-y=8, xy+z2=-16.

Verification: x+y+z=0 (in 10)

2. As shown in the figure, AB‖CD, the number of times to find ∠ 1+∠2+∠3+∠4. (in 10)

Read the following article first, and then answer the questions.

A food research department wants to mix A, B and C into 100 kg food, and it is stipulated that at least 44,000 units of vitamin A and 48,000 units of vitamin B are needed in the mixed food. The contents of vitamins A and B in the three foods are shown in the following table.

Table 1

A, B and C.

Vitamin A (unit/kg)

Vitamin B (unit/kg)

Table 2

Production cost per kilogram (yuan)

A species

B 12

C 8

Assume that the quality of three kinds of food developed and produced is X kg, Y kg and Z kg respectively.

① Try to list the equations and inequalities according to the meaning of the question, and prove that: y≥20, 2x-y≥40.

(2) Let the production costs of three kinds of food A, B and C be shown in Table 2, and try to express the total cost P of mixed food with X and Y; If the mass of food A in mixed food is limited to 40 kg, try to find out the range of total cost P at this time and determine the mass of food B and C when P is the minimum. (out of 20)

Mathematical calculation problem, important process, thank you for your answer.

Primitive formula

=(√3- 1)+3-2√3+2× 1/2

=(√3-2√3)+(3- 1+ 1)

=3-√3

Seventh grade calculation problem: Wen Ku. Baidu, please. /view/A6EAFB23482FB4DAA58D4BB5。 Some of them are inequality groups of applied problems.

1、2X+3>0

-3X+5>0

2、2X0

3, 5x+6 < 3x

8-7X>4-5X

4、2( 1+X)>3(X-7)

4(2X-3)>5(X+2)

5、2X0

6、 1-X>0

X+23

X+23/2X-3

10、 1+ 1/2X>2

2(X-3)≤4 can only find so much. Sorry, you can go to Baidu Library.

Please adopt it.

The process of calculating 100 in grade seven is 1. 3/7 × 49/9-4/3.

2.8/9 × 15/36 + 1/27

3. 12× 5/6 – 2/9 ×3

4.8× 5/4 + 1/4

5.6÷ 3/8 – 3/8 ÷6

6.4/7 × 5/9 + 3/7 × 5/9

7.5/2 -( 3/2 + 4/5 )

8.7/8 + ( 1/8 + 1/9 )

9.9 × 5/6 + 5/6

10.3/4 × 8/9 - 1/3

0. 12χ+ 1.8×0.9=7.2 (9-5χ)×0.3= 1.02 6.4χ-χ=28+4.4

1 1.7 × 5/49 + 3/ 14

12.6 ×( 1/2 + 2/3 )

13.8 × 4/5 + 8 × 1 1/5

14.3 1 × 5/6 – 5/6

15.9/7 - ( 2/7 – 10/2 1 )

16.5/9 × 18 – 14 × 2/7

17.4/5 × 25/ 16 + 2/3 × 3/4

18. 14 × 8/7 – 5/6 × 12/ 15

19. 17/32 – 3/4 × 9/24

20.3 × 2/9 + 1/3

2 1.5/7 × 3/25 + 3/7

22.3/ 14 ×× 2/3 + 1/6

23. 1/5 × 2/3 + 5/6

24.9/22 + 1/ 1 1 ÷ 1/2

25.5/3 × 1 1/5 + 4/3

26.45 × 2/3 + 1/3 × 15

27.7/ 19 + 12/ 19 × 5/6

28. 1/4 + 3/4 ÷ 2/3

29.8/7 × 2 1/ 16 + 1/2

30. 10 1 × 1/5 – 1/5 × 2 1

3 1.50+ 160÷40 (58+370)÷(64-45)

32. 120- 144÷ 18+35

33.347+45×2-4 160÷52

34(58+37)÷(64-9×5)

35.95÷(64-45)

36. 178- 145÷5×6+42 420+580-64×2 1÷28

37.8 12-700÷(9+3 1× 1 1) ( 136+64)×(65-345÷23)

38.85+ 14×( 14+208÷26)

39.(284+ 16)×(5 12-8208÷ 18)

40. 120-36×4÷ 18+35

4 1.(58+37)÷(64-9×5)

42.(6.8-6.8×0.55)÷8.5

43.0. 12× 4.8÷0. 12×4.8

44.(3.2× 1.5+2.5)÷ 1.6 (2)3.2×( 1.5+2.5)÷ 1.6

45.6- 1.6÷4= 5.38+7.85-5.37=

46.7.2÷0.8- 1.2×5= 6- 1. 19×3-0.43=

47.6.5×(4.8- 1.2×4)= 0.68× 1.9+0.32× 1.9

48. 10. 15- 10.75×0.4-5.7

49.5.8×(3.87-0. 13)+4.2×3.74

50.32.52-(6+9.728÷3.2)×2.5

Sorry, I only found 50 items, please forgive me!

I am the worst at math in the second volume of the seventh grade. I will be in the eighth grade when I start school, and 40% of the seventh grade math problems will not be done.

A seventh grade math problem! ~ ~ ~ Hurry up, process flow! ~ ~ ~ Original formula =[(a+2b)-3][(a+2b+3]]

At this time, the square difference formula is used.

Original formula =(a+2b)? -3? =a？ +4ab+4b？ -9

Find 50 linear equations in the seventh grade. Note: It is a calculation problem, not a practical one. Thank you for your linear equation:

1.2(x-2)-3(4x- 1)= 9( 1-x)

2. 1 1x+64-2x = 100-9x

3. 15-(8-5x)=7x+(4-3x)

4.3(x-7)-2[9-4(2-x)]=22

5.3/2[2/3( 1/4x- 1)-2]-x = 2

6.2(x-2)+2=x+ 1

7.0.4(x-0.2)+ 1.5=0.7x-0.38

8.30x- 10( 10-x)= 100

9.4(x+2)=5(x-2)

10. 120-4(x+5)=25

1 1. 15x+863-65x=54

12. 12.3(x-2)+ 1 = x-(2x- 1)

13. 1 1x+64-2x = 100-9x

14. 14.59+x-25.3 1=0

15.x-48.32+78.5 1=80

16.820- 16x=45.5×8

17.(x-6)×7=2x

18.3x+x= 18

19.0.8+3.2=7.2

20. 12.5-3x=6.5

2 1. 1.2(x-0.64)=0.54

22.x+ 12.5=3.5x

23.8x-22.8= 1.2

24. 1\ 50x+ 10=60

25.2\ 60x-30=20

26.3\ 3^20x+50= 1 10

27.4\ 2x=5x-3

28.5\ 90= 10+x

29.6\ 90+20x=30

30.7\ 69 1+3x=700

3 1 x+5=8

32 3x+5( 138-x) = 540

33 x-5=3

34 2x- 10.3x= 15

35 0.52x-( 1-0.52)x=80

36 x/2+3x/2=7

37 3x+7=32-2x

38 3x+5( 138-x)=540

39 3x-7(x- 1)=3-2(x+3)

40 18x+3x-3 = 18-2(2x- 1)

4 1 3(20-y)= 6y-4(y- 1 1)

42 -(x/4- 1)=5

43 3[4(5y- 1)-8]=6

44 ^ 2(x-2)+2 = x+ 1

45 ^ 2(x-2)-3(4x- 1)= 9( 1-x)

46 x/3 -5 = (5-x)/2

47 2(x+ 1)/3 = 5(x+ 1)/6- 1

48( 1/5)x+ 1 =(2x+ 1)/4

A calculation problem (important process) thank you = (1/2) * (1-1/3)+(1/2) * (1/3-/5) ...

=( 1/2)*( 1- 1/3+ 1/3- 1/5+……+ 1/2007- 1/2009)

=( 1/2)*( 1- 1/2009)

= 1004/2009

Calculation problem (A 2-B 2) ÷ (A-B) Important process Thank you (A 2-B 2) ÷ (A-B)

=(a+b)(a-b)÷(a-b)

=a+b