7 math problems 20

2. Solution: The number of workers recruited for type A is x people, the number of workers in type B is nx n 2) The total monthly wage of the recruited workers is y yuan, then y 600x+1000nx Because with the increase of the number of workers in type B, when the number of workers in type B is twice the number of people in type A, n 2, the monthly wage paid is the least. Therefore, recruiting 50 people for type A and 100 people for type B can make the minimum monthly salary paid is 130,000 yuan. 3 1008 100 9 = 900 yuan 1314 9 = 112 Solution Set up tour group A has x people Tour group B has 112-x people.

11x+13 112-x =1314 11x+1456-13x=1314 -2x+1456=1314 -2x=-142 x=71 112-x=112-71=41 people A: There are 71 people in tour group A There are 41 people in tour group B. 4. Let the number of additional passengers per minute be x (A+30X) 30=(A+10X) 20 x = A 30 The number of passengers per minute at each ticket gate is A 15, and the number of ticket gates required is [A+5*(A 15)] [(A 15)*5]=4 As for the additional reward points, it's up to you 22 A unit has built a new building, and water pipes need to be laid from the main water pipeline at a distance of 132 meters, and there are two specifications of water pipes of 8 meters and 5 meters long. Please design a plan How to choose these two kinds of water pipes in order to be laid from the main pipe to this building There are several such schemes: If the 8-meter-long water pipe is 50 yuan each, the 5-meter-long water pipe is 35 yuan each, choose which plan is the most cost-effective Solution: Set up 8 meters of water pipe x root 5 meter water pipe y root 8x+5y=132 solution x=4 y=20 x=9 y=12 x=14 y=4 from the title Because it is necessary to save the most money, so when there are 14 8-meter-long water pipes and 4 5-meter-long water pipes, it is the most cost-effective.

If you enter with 200 yuan, then A buys 200 (1+30%) equals 260 B buys 200 (1+20%) = 240 The difference in their unit price is 260-240=20 but buys 8000 more, so A buys 8000 more than B divided by 20=400 A; Bought 400 more pieces by the way . This is the first time I've answered a question for a netizen. Wish...

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1: Unit price of store A = 200 * (1 + 30%) = 260 unit price of store B = 200 * (1 + 20%) = 240

If store A sells x pieces, then store B sells 2x

260x+8000=240*2x

The solution is x=

Let the first addition be X

A+x) (10+x)=3 5

B (10+x)=2 5

2x+a) (10+x)=7 10

B (10+x)=3 10

The above four formulas are combined with x=5kg, A=4kg

So it turns out that there are 4kg in the alloy A and 5kg is added to the first time

Let the speed of the two people be x ym seconds.

Encounters with backs. 30（x+y）=200

240 in the same direction (x-y)=200

Simplification x+y=20 3

x-y=5/6

The solution is x=15 4 m s

y=5/3 m/s

Let one velocity be x and one y

30x+30y=200(1) 4*60x+200=4*60y(2) can be obtained by combining the 2 types.

A: m-second B: m-second or A: m-second B: m-second.

200/(x+y)=1/2

200/(x-y)=4

The simultaneous solution gives x=75 (meters per minute) and y = 50 (meters per minute), so they are 75 (meters per minute) and 50 (meters per minute), respectively

Solution: Draw a picture on the book first.

Extend Ad to E so that de=ad, connect Be, then be=ac=8 in δabe, according to the sum of the two sides greater than the third side, there is:

ae ab -be = 2

Therefore: 2< ae <18, and ae = 2ad, therefore: 1

It's a pity that there is no diagram, the conditions are not clear, and there are other possibilities for any straight line that crosses point A.

Is it the parents who find the questions for the students to do???

7x9x65(2 6+1)(2 12+1)(2 24+1) is answered by the oak between 60 and 70 and 63 and 652) (a+1) (a)-(a+2) (a+1)(a+1)(1+a) a(a+1)-a(a+2) a(a+1)(a+1) 2-a(a+2) a(a+1)1 a(a+1).

So (2008 2007) - (2009 2008) = 1 (2007x1 2008).

That big brother, I am blind to you, a=2008 2007=1+1 2007>b=2009 2008=1+1 2008, this can be the wrong bridge to shut up...

1, = (2 to the 24th power + 1) (2 to the 24th power - 1) (2 to the 24th power + 1) (2 to the 12th power + 1) (2 to the 12th power - 1) (2 to the 24th power + 1) (2 to the 24th power + 1) (2 to the 6th power + 1) (2 to the 6th power - 1).

2 to the 24th power + 1) (2 to the 12th power + 1) *65*63, so these two numbers are 63 and 65

2、a=1+ 1/2007 b=1+ 1/2008a>b

2 to the 48th power minus 1

2 to the 24th power + 1) (2 to the 24th power of the Kiriyama square -1) (2 to the 24th power + 1) (2 to the 12th power + 1) (2 to the 12th power - 1) (2 to the 24th power + 1) (2 to the 12th power + 1) (2 to the 6th power + 1) (2 to the 6th power - 1).

2 to the 24th power + 1) (2 to the 12th power + 1) * 65 * 63 so these two numbers are 63 and 65 in socks

a = 2008 molecule 2007 = 1-1 2008b = 2009 molecule 2008 = 1-1 2009 because 1 2008>1 2009 so a

2a-1)^2+|3b-1|=0

by non-negativity. 2a-1=0

3b-1=0

Solution. a=1/2

b = 1 35 (3a square b - ab squared) - (ab square + 3a square b).

A: There are x students and x 30 students.

It can be obtained from the title, A travel agency cost = 500 + 50% * 500x = 500 + 250x B travel agency cost = 500 * 60% + 60% * 500x = 300 + 300x When A cost = B cost, 500 + 250x = 300 + 300x can get x = 4 people, when A costs B cost, 500 + 250x 300 + 300x can get x 4, people, x is greater than or equal to 30 people from the title, so you should choose A travel agency.