There are three ways of the one dimensional one dimensional equation in the first year of junior hig

1。A bank has set up student loans for college students, which are divided into 3 4 years and 5 7 years, and the annual interest rate of the loan is21%, 50% of the loan interest is subsidized by the state finance, a college student is expected to be able to repay 10,000 yuan in a lump sum after 6 years, and asked him how much he can borrow now?

accurate to 10,000 yuan).

Solution: Suppose he can now borrow about x million yuan, according to the topic, get, x+6 x

To solve this equation, we get, x

After testing, it is in line with the topic.

A: He can now borrow about 10,000 yuan.

2。Answer the following questions and compare their differences:

1) The master and apprentice overhaul a 180-meter-long water pipeline, the master overhauls 15 meters per hour, and the apprentice overhauls 10 meters per hour.

Solution: Set x hours to complete the maintenance of the entire pipeline, according to the topic, get, 15x+10x=180

To solve this equation, we get, x

After testing, it is in line with the topic.

Answer: The maintenance of the whole pipeline can be completed in hours.

2) The master and apprentice cooperate on a gas pipeline, it takes 10 hours for the master to complete alone, and 15 hours for the apprentice to complete it alone.

Solution: Let x hours complete the maintenance of the entire pipeline, according to the topic, obtain, 1 10x+1 15x=1

To solve this equation, we get, x=6

After testing, it is in line with the topic.

A: The whole pipeline can be overhauled in 6 hours.

3.The school is preparing to purchase a batch of desks and chairs, and the original order is 60 sets, each set of 100 yuan. The store said: If you buy more, you can get a discount, but the school bought 72 sets, each with a price reduction of 3 yuan, but the store got the same profit, and asked for the cost of each set of desks and chairs.

Solution: Let the cost of each set of desks and chairs be x yuan, according to the topic, 60 (100-x) = 72 (100-3-x).

To solve this equation, we get, x=82

After testing, it is in line with the topic.

A: The cost of each set of desks and chairs is 82 yuan.

1.Let's ask him about $00,000 in loans now.

2.(1) Set x hours to complete the maintenance of the entire pipeline.

15+10）x＝180

2) Set x hours to complete the maintenance of the entire pipeline.

x/10）+（x/15）＝1

3.The cost of each set of desks and chairs is $x.

100×60-60x＝72×（100-30）-72x

Solution: Let's ask him about $00,000 in loans now.

So, answer: 1) Solution: The maintenance of the entire pipeline can be completed in x hours.

Well, (15+10) x 180

Answer: 2) Solution: The maintenance of the whole pipeline can be completed in x hours.

Then, (x 10) + (x 15) 1

A: 3Solution: The cost of each set of desks and chairs is X yuan.

Well, 100 60-60x 72 (100-30)-72x A:

3x+2y-5x-7y

Mixed addition, subtraction, and operation of rational numbers.

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About rational number calculation questions and answers.

Who has a rational number calculation problem in the first year of junior high school (I want 1000 questions).

Write a primary school mathematics teaching software, mainly to test the lower grades of primary school.

Check out the same topic question: Mixed operations on rational numbers.

Others: 1 in total.

1 Calculation Questions.

2.Calculation problem: (10 5 = 50).

3x+2y-5x-7y

1) Calculation Questions:

16)4a)*(3b)*(5c)*1/6

a^3-2b^3+ab(2a-b)

a^3+2a^2b-2b^3-ab^2

a^2(a+2b)-b^2(2b+a)

a+2b)(a^2-b^2)

a+2b)(a+b)(a-b)

x^2+y^2)^2-4y(x^2+y^2)+4y^2(x^2+y^2-2y)^2

x^2+2x)^2+3(x^2+2x)+x^2+2x+3(x^2+2x)^2+4(x^2+2x)+3(x^2+2x+3)(x^2+2x+1)

x^2+2x+3)(x+1)^2

a+1)(a+2)+(2a+1)(a-2)-12a^2+3a+2+2a^2-3a-2-123a^2-12

3(a+2)(a-2)

x^2(y+z)^2-2xy(x-z)(y+z)+y^2(x-z)^2

x(y+z)-y(x-z)]^2

xz+yz)^2

z^2(x+y)^2

3(a+2)^2+28(a+2)-20

3(a+2)-2][(a+2)+10]

3a+4)(a+12)

a+b)^2-(b-c)^2+a^2-c^2(a+b)^2-c^2+a^2-(b-c)^2(a+b+c)(a+b-c)+(a+b-c)(a-b+c)(a+b-c)(a+b+c+a-b+c)

2(a+b-c)(a+c)

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

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

x^2+x)^2-(x^2+x)-2

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

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

I did my best!

y=2x-7。。。Formula.

5x+3y+2z=2。。。Two-form.

3x-4z=4。。。Three-style.

From the three formulas z=3x 4-1... Four Forms.

Four formulas and one formula are substituted into two formulas together, and there are 5x+3(2x-7)+2(3x 4-1)=2 solutions to x=42 25... Five formulas.

Substituting five formulas into one formula yields y=-91 25

Substituting the fifth formula into the fourth formula gives z=-13 50

It is obtained by 4x-3y-3z=0, x-3y+z=0

4x-3y=3z……①x-3y=-z……, 3x=4z, and x=4z 3

Take x=4z 3 generations, 4z 3-3y=-z, and get y=7z 9 x=4z 3 y=7z 9 generations x 2+y 2+z 2 xy+yz+zx.

x^2+y^2+z^2)/(xy+yz+zx)=(16z²/9+49z²/81+z²)/(28z²/27+7z²/9+4z²/3)

1. It is 8x-4-9x+3=8x+32, and the solution is x=-11 3

2. It is 10x-3=1-5x+28, and the solution is x=32 15

3. It is 6x-2-12+6x+12=18x-18, and the solution is x=8 3

Respectively, from top to bottom imitation of the bureau marked as, the bridge is so convenient. ，4x+z=-14 ④

Min Yu +, 5x-z=-13, 9x=-27, x=-3, bring in, z=-2 substitution, y=-2

This is called the elimination method.