Elementary 2 Math Problem Solving Equation 25 in the sub test

A and B respectively from the destination 6 kilometers and 10 kilometers away from the two places at the same time, A and B speed ratio is 3:4, the result A arrives at the destination 20 minutes earlier than B, find the speed of A and B.

Solution: Let the number of copies per serving be x(km min).

6÷3x+20=10÷4x

Shift 6 3x-10 4x=-20

Merge -1 2x=-20

The coefficient is x=1 40

So A's speed = 3x=3 1 40=3 40 (km min) B's speed = 4x=4 1 40=1 10 (km min) Zhang Ming counted half of a batch of books in 4 hours, Li Qiang joined the work of counting the other half of the books, and the two cooperated to count the other half of the books in 1 hour, if Li Qiang counted this batch of books alone, it would take a few hours.

Solution: Suppose it takes X hours for Li Qiang to count these books alone.

1/2=1/2÷4+1/x

1/2=1/8+1/x

Shift 1 2-1 8 = 1 x

Merge 3 8 = 1 x

The coefficient is x=8 3

Answer: If Li Qiang counted this batch of books alone, it would take 8 to 3 hours.

1.Let A's velocity be 3x B's velocity be 4x

10/4x-6/3x=20 x=

So the velocity of A is.

B's velocity is.

2.Set: Zhang Ming's speed of counting books is x h Li Qiang's speed is y h The time when Li Qiang finished counting books is z

4x=(x+y)*1 gives y=3x

8x=yz gives 8x=3xz

z=8x/3x

z=8 3 hours.

1 Let A's velocity be 3x, then B's velocity is 4x

10/4x-6/3x=20/60

x=2 33x=2 4x=8 3 (1 hour)2 It takes x hours for Li Qiang to count this batch of books alone.

1/2)/4+1/x=1/2

x = 8 for 3 hours.

Solution: 2x=3-

2×｛2（x-1）｝

Go to the denominator. Multiply by 2 (x+1))2x=

3-4x+26x=555x

Check: Substitute x into 2 (x+1) ≠ 0

665 so.

x=——— is the root of the primitive fraction.

Wait a minute, me.

I'm going to eat. I'll help you figure it out later)6

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First put the 2 of 2x-2, and then divide each co-multiplication x-1 about two fractions to solve it.

If you buy x pieces of small commodities for the first time, the unit price of this small commodity for the first time is 5 x (yuan). Because the second time every dozen price reduction, then each price reduction is, the unit price of the second small commodity is (5, and the number of small goods purchased for the second time is 2x, a total of 2 yuan, the equation is.

Suppose he buys x pieces for the first time, the unit price is 5 x yuan, and the second time he buys 2x pieces.

2x * 5/x）- 2x/12) = 2

The solution is x=60

If the first x pieces are set, each piece will be (5 x) yuan;

Now 2 (2x)=1 x yuan per piece.

According to the title, the price of each 12 items is.

12(5/x)

i.e. 60 x-12 x=

48/x=x=60

So, buy 60 pieces for the first time.

Solution: Let's say the first time he bought a small commodity, it was x.

5 / x -2 / x＋10=

Solution: x1=50, x2=-15

After testing, x1=50 and x2=-15 are both solutions to the original equation, but x2=-15 is not in line with the topic, so he can only take x1=50 Answer: He bought 50 small commodities for the first time.

Suppose he buys x pieces for the first time, the unit price is 5 x yuan, and the second time he buys (x+10) pieces, so.

x+10）/12*（12*5/

x1 = 50, x2 = -15 (rounded).

Bought 50 pieces for the first time.

Set purchased x pieces for the first time.

5 x = x 12 times 2

Solve x=120 and then test it.

I don't know whether x+3 (1) is the denominator or (2) x is the denominator (choose the following two ways).

1) Multiply x(x+3) by the left and right sides of the equation at the same time

5x=x+3

x=3/42）5/x+3=1/x

The left and right sides of the equation are multiplied by x at the same time

Get 5+3x=1

The solution yields x=-4 3

x+1/x-1 - 4/x^2-1=1

The left and right sides of the equation are multiplied by x 2-1 at the same time

Get (x+1) 2-4=x 2-1

Simplification 2x=2

Solution x=1

Solution: 1: 5x x 3

4x＝3x＝3/4

It is examined that x 3 4 is the solution of the original equation.

2： （x＋1）²－4＝x²－1

x²＋2x＋1－4＝x²－1

2x＝2x＝1∵x－1＝1－1＝0

There is no solution to this equation.

1.Original=5x=x+3

x=3 4 test can be seen to be in line with the topic.

2 original = x square + 2x - 4 = x square - 1

The x=1 test shows that there is no solution.

We've just done it

You have to remember that it is not possible to solve fractional equations.

Then if you look at it, move 1 x to the left and move +3 to the right, so does +3 become -3? (Change the number of the move item).

Then multiply each item by x to get 5-1=-3x

Then the equation becomes an integral equation. Will it be solved, right?

5 x+3=1 x on both sides at the same time gives 5+3x=1 solution x=-4 3

Let's assume that the number of yearlings randomly inspected by the quality inspection department of the finch brigade is x (the same as A and B), then the equation can be listed:

a) 48 x - 45 x = 5%.

3/x=5%

x = 60 2) The pass rate of factory A products = 48 x * 100%, your Fang Min and Wang Cheng are listed wrong.