Ask for answers!! Mathematics solves equations in one way at a time!!

Solution: If x sheets are used for the box body, then 108-x is used for the bottom of the box.

Get a box body 15x

Get the bottom of the box 42 (108-x).

According to the inscription, 15x=42(108-x) 215x=21*108-21x

36x=21*108

x=63Answer: Use 63 sheets to make the body of the box, then use 45 to make the bottom of the box.

Solution: Set the box body with x sheets, and make the bottom of the box with Y sheets.

Analysis: Because there are now always 108 tin box bodies and bottoms. So x+y=108

Formula; The number of sheets of the body of the box + the number of sheets of the bottom of the box = the total number of sheets of white iron sheets made of canned food boxes 108Equation (1) is derivedAnd because now a box body and two box bottoms are matched to form a set of canned food boxes.

So; The number of boxes * 2 = the number of boxes at the bottom. This will make them equal. Equation (2) 2*15x=42y

x+y=108 (1)

2*15x=42y (2)

108-y=x (3) from (1).

Substitute (3) for (2);

30(108-y)=42y

y=45 and y=45 are substituted into (1) to obtain: x=63

So; x=63

y=45A: Use 63 sheets to make the body of the box, and use 45 to make the bottom of the box.

Solution: It can be made into x a complete set of canned food boxes.

108=（1/15+2/42）x

108=36/315x

x=108/36*315x=945

A: It is used to make 63 pieces of box body and 45 pieces of box bottom.

Idea: Take the total number of canned food boxes and the ratio of the box body to the bottom of the box to list the equation, and find the equal relationship.

Solution: If the box body is made of x sheets, then the bottom of the box is made of (108-x) sheets.

2*15x=42(108-x)

Solve the equation. x=63

Answer: 63 sheets of iron sheet should be used to make the box body, and 45 sheets should be used to make the bottom of the box.

This is a companion problem to the application problem of unary equations, and the key is to find the equality relationship.

Solution: If x sheets are used as the box body, then (108-x) sheets are used as the bottom of the box.

15x=42*(108-x)/2

x=63A: Use 63 sheets for the body of the box, and 45 sheets for the bottom of the box.

Solution: It can be made into x sets of canned food boxes.

From the meaning of the title: a piece of iron sheet can make 15 pieces of box body, that is, 1 15 pieces of iron sheet are needed to make a box body; There are 42 pieces of a box bottom made of iron sheets, that is, 1 42 pieces of iron sheets are needed to make a box bottom.

Columnable equation 1 15 x +1 42 multiplied by 2 x = 108 gives x = 945

Rub.,I read the wrong question.。。。

Set x sheets as the bottom of the box.

42x*2=（108-x）*15

Just solve it.

Suppose x sheets are used to make the body of the box, then 108-x sheets are made of the bottom of the box. According to each sheet can be made into 15 box bodies or 42 box bottoms, a box body and a box bottom are equipped with a set of canned food boxes, and the equation 2*15x=42*(108-x) can be listed to obtain x=63 in the equation

Set the barrel depth to xcm. Rule.

x (1-1 3) + x (1-1 5) = 55 to get x = 20

The barrel depth is 20cm.

Solution: The long one is x centimeters, then the short one is (55-x) centimeters x (1-1 3) = (55-x) (1-1 5) x = 165 8

x = 30 depth in the barrel: 30 (1-1 3) = 20 cm.

Solution: It takes X years to pay off in one lump sum.

40+40*15%x=(

20x=40

x=2A: It takes 2 years to pay off in one lump sum.

Do it yourself, use your brains more, and live a long life

It means that in the second year, Xiao Ming's family has paid 30,000 yuan (the down payment), and there is 90,000 yuan left, and the interest on these money is 90,000 yuan), plus 5,000 yuan, Xiao Ming needs to pay a total of 5,360 yuan in the second year. (The interest is not counted within 120,000 yuan, that is, Xiao Ming's remaining money in the third year is 85,000 yuan, not 84,640 yuan).

Let's start the column equation:

Solution: Set: Xiao Ming's family needs to pay 5,200 yuan in the first year.

90000-5000（x-1）=（5200-5000）÷90000-5000x+5000=5000095000-5000x=50000

5000x=45000

x=9A: In the 9th year, Xiao Ming's family needs to pay 5,200 yuan.

1.In February, male x, female y

x+y=6 unary.

Male = x, female = 6-x

x=,y=2.Let the river slope be x

x=800

1.The sales revenue of men's and women's clothing in February was x, 6-x million yuan (1 + 40%) x + (1 + 64%) (6-x) = 9x=, and the sales revenue of men's and women's clothing in February was 10,000 yuan.

2.There are x hectares of river slopes.

x = 800 river slopes with 800 hectares.

1.In February, the sales revenue of men was x million yuan, and the sales revenue of women's clothing was y million yuan x + y = 6 - > 35 x + 36y = 210

140x+164y=900-->35x+41y=2256y=15，y=5/2=，x=7/2=

In February, the sales revenue of men was 10,000 yuan, and the sales revenue of women's clothing was 20,000 yuanThere are x hectares of river slopes.

According to the topic: 3900 + 3x = 5500 + x

2x = 5500-3900 = 1600, x = 800 river slopes have 800 hectares.

Let the original length be x meters.

x*(1-1/2)*(1-1/3)*(1-1/4)*.1-1/2010)=1

x*1/2010=1

x=2010

The original length is 2010 meters.

Solution: The original length of the rope is x meters, and the title is derived

1-1/2）*（1-1/3）*（1-1/4）……1-1/2010）x=1

1/2010 *x=1

x=2010

A: The original length of the rope is 2010 meters.

Solution: Let the original length of the rope be x meters.

x*1/2*2/3*3/4*……2009/2010=1x*1/2010=1

x=2010

A: The original length of the rope is 2010 meters.

Idea: Solve the problem with the remaining equiquantitative relationship. During the calculation, the denominator of the previous fraction is reduced to the numerator of the next fraction.

Solution: Let the original length be x

Then there are x-1 2x-(1 2*1 3)x-(1 2*2 3*1 4)x-..1\2*2\3*3\4*..1\2010)x=1

i.e. x-1, 2x-1 (2*3), x-1 (3*4)x-..1\(2009*2010)x=1

The split term is x-1 2x-(1 2-1 3)x-(1 3-1 4)x-..1\2009-1\2010)x=1

i.e. x-1 2x-1 2x+1 3x-1 3x+1 4x-..1\2009x+1\2010x=1

1 2010x=1

So x=2010

Solution: The original length of the rope is a meter, which can be obtained from the title

1-1/2）×（1-1/3）×（1-1/4）×…1-1/2010）×a=1

1/2 x 2/3 x 3/4 x…x 2009/2010 x a=1

Approximately: 1 2010 x a = 1

a=2010

A: The original length of the rope is 2010 meters.

Set the original rope length a

a*1/2*2/3*3/4...2009/2010=1

The numerator and denominator are multiplied and eliminated.

a=2010

Solution: Set the rope length to x meters.

x(1/2)(2/3)(3/4)(4/5)(5/6)……2008/2009)(2009/2010)=1

x(1*2*3*4*5……*2009)/(2*3*4*5*6……*2010)=1

x(1/2010)=1

x=2010

A: The rope length is 2010 meters.

Suppose the rope is long x

What is left after the first subtraction: x*(1-1 2).

What is left after the second cut: x*(1-1 2)*(1-1 3)After the third cut, it is left: x*(1-1 2)(1-1 3)(1-1 4).

The 2009th cut off the remaining 1 2010, and the remainder was: x*(1-1 2)(1-1 3)(1-1 4).1-1/2010）

So: x*(1-1 2)(1-1 3)(1-1 4).1-1/2010）=1

Solve this equation:

x*（1-1/2）（1-1/3）（1-1/4）..1-1/2010）

x*（1/2）（2/3）（3/4）..2009 2010) The denominator of the former term is the same as the molecular formula of the next term, which can be approximated: =x* 1 2010

x/2010=1

x = 2010 (m).

Let the length of the rope be x, then.

The first time minus half of it, there is still (1-1 2) x the second time minus the remaining third, there is still (1-1 2) (1-1 3) x the third cut off the remaining quarter, and there is (1-1 2) (1-1 3) (1-1 4) x

.Until the remaining 2010 is cut off, there is still (1-1 2) (1-1 3) (1-1 4)*1-1/2010)x=1

i.e. (1 2)*(2 3)*(3 4)*(4 5)*2008/2009)*(2009/2010)x=(1/2010)x=1

then x = 2010 (m).

Solution: If the cost price of each product should be reduced by x yuan, then according to the question [510(1-4%)-400-x)] m(1+10%)=m(510-400), solve this equation to get x=

A: The cost price of each piece of the product should be reduced by yuan

This question has a large amount of text description, it is necessary to review the topic and find the equivalent relationship: the sales profit (sales profit = sales price - cost price) remains unchanged, and the cost price of each product should be reduced by x yuan, then the sales price of each product is 510 (1-4%) yuan, the sales (1+10%) m pieces, the new sales profit is [510 (1-4%)-400-x)] 1+10%) m yuan, and the original sales profit is (510-400) m yuan, and the column equation can be solved

Let the adjusted cost be $y;

510-400) m = braces 510 here (100%-4%-y, braces m (100%+10%)

y=meta again.

Set a price reduction of X yuan per piece.

510-400）*m=(510-x)*

It can be calculated that x=410

Try to use it as much as possible.

It's simple. I think it's all nonsense after this question. Because of a three-digit number, the sum of the digits in the three digits is 24, and the number in the ten digit is 2 smaller than the digit in the hundred.

There's so much nonsense in the back. You can think of it. If the sum is 24, then the average is 8.

And the number on the ten digit is smaller than the number on the hundred, 2 only, 9 and 7, then this 3-digit number is 978.

He later says 978--99=879

formal solutions; Let the hundred digits be

100ㄨ+10x（ㄨ-2）+24-ㄨ-2）-11ㄨ=100x（24-ㄨ-2）+10x（ㄨ-2）+ㄨ

9 decenchy, 9-2=7 single digits, 24-9-7=8, this 3-digit number 978

However, I still use the latter condition for this solution. You can think of it the same way. Suppose the ten digits are the same as the hundreds, then the sum of the three digits is 26.

The sum is 26, and there is only a combination of 9, 9, 8 (Note: even if the 3 maximum numbers are 999, the sum is only 27 and 1 more than him), so this number is 978