A few math problems in the first year of junior high school Thank you, a few math problems in the fi

One: d (wrong).

2. Actual value: 134 + 500 + (466 - (500 * yuan.)

Saved: 654-466-134=54 yuan.

If you buy it together, it will only cost 500* yuan.

And buy it separately: 134 + 466 = 600 yuan.

Buying together saves you more than buying separately: RMB.

So it's more cost-effective to buy together.

The third question can also be understood in this way: because the second consumption of 466 yuan, the actual amount has actually exceeded 500 yuan, so if you need to buy together, then the amount of 134 yuan in the first transaction belongs to the amount of more than 500 yuan, and it should be discounted by 20%, so it must be cheaper together, and the cheap amount is the amount of 134 and 80% off: 134 * (yuan.)

Three: 1, (1) 3; （2）

2. (1) No, no

The first question should indeed be 3), the second question: (1): 134 yuan, 520 yuan (500 + 16 (2): j saved 54 yuan (520-466 = 54) (3:): 500 * yuan.

Can save yuan Question 3 2) It's a bit troublesome, it's too late to do it = =!

2) 134 200, so there is no discount.

When 500 yuan, the preferential price is yuan, so pay 450, 466-450=16, indicating that 16 yuan is the price after 20% discount, 16 yuan,,, so the second time should be 520 yuan, 54 yuan.

If you buy it once, the total value is 134 + 520 = 654 yuan, and you need to pay: 500 * yuan, so it is cost-effective to buy at one time.

1, C2, (1) 134 + 500 + 20 = 654 yuan.

2) 54 yuan.

3) Loss, because the first time there was no discount.

2）7/4≤x<9/4

1 Let =km+k-1 2 m+x=m+k==4 +=3

2) 40 and 15 17-|42 and 18 19-83 and 15 17|40 and 15 17-83 and 15 17 + 42 and 18 19-43 + 42 and 18 19

and — 1 3 and minus — 3 10 difference.

According to the inscription.

The difference between 2 1 3 and —1 3 is the sum of —1 1 2.

According to the inscription.

2 and 1 3 - (-1 3) + (1 and 1 2).

2 and 1 3 - (-1 3) + (1 and 1 2).

2-1 and 1 2

3 and 1 2 columnar calculation: How much smaller is the sum of 4 and -5 than the opposite of --5? > column according to the inscription -(5)-[4+(-5)].

Original = 5-(-1).

3,, how much is the absolute sum of the three numbers greater than the absolute value of the sum of the three numbers.

According to the inscription. 3|+|

Original = (3+

2010÷4=502……2

Every group of 4, and the sum is -4, and then the calculation is very simple.

The answer is 3013. Ideas: The first three numbers 1 plus 2 minus 3 are equal to zero, and the negative 4 plus 5 in the back is equal to 1, and so on, negative 6 plus 7 is also 1, it can be found that from 4 to 2009 has been this law, so it is equivalent to 1003 1s added, and finally add a 2010.

Question 1, 2

In the second question, the upper bottom is 2a 2-a=a-2, the lower bottom is 3(a-2), and the waist length is 2a, so the trapezoidal circumference is a-2+3(a-2)+2*2a=8a-8

Question 3, the original selling price is (1+, and the current selling price is profitable.

Solution 1, equation 2x +3kxy+y -6xy+9 without xy term 3kxy-6xy=0

k = 22, from the top bottom is 1 2-2 cm less than the waist, so the upper bottom is a -2 cm long, so the height is 3 a - 6 cm.

Triangle hypotenuse calculation formula = length * width.

Hypotenuse = 3a-6 + a-2 = 4a-8

So the circumference is 2 4a-8 + a-2 + 3a-6 = 2 4a-8 + 4a-83, the selling price.

Profit adoption oh.

Answer: 1. The coefficient is the number in front of the letter except for the letter, and the symbol is also included, when the general coefficient is 1, it will be omitted, so the coefficient of this question is -1; The number is the sum of the number of all letters, and the general number is 1 and is omitted, so the number is: 1 + 3 + 2 = 6.

2. Understand the monomials: numbers, letters, the product of numbers and letters, and the product of letters and letters.

Understand that the number is 5, which means that the sum of the times of x and y is 5;

So for example: x to the 3rd power and y to the 2nd power;

3. Reduce the price by 4%, which is easier to understand

Original price - reduced ** = current **.

a-a*4%

4. According to the method of the first question, the answer is: coefficient = -2 7;

Number = 5;5. According to the conditions, it can be obtained: -m=-2, so m=2;

The problem is slightly wrong: it should be to the nth power of x, according to the number of monomials is 3, the equation can be columned: 2+na=3, so n=1.

6. The answers are: -5,0 times; - 1,2 times; , 3 times; -5 7,1 times; 4 5, 4 times; 25,4 times.

7. Classification according to the positive and negative coefficients:

Positive coefficient: 3 x to the power of 3a; bxy;5x squared; a to the 3rd power; 1 2axy squared.

Negative coefficient: -4b squared y; -b squared x squared.

According to the number of times: quadratic: 5x squared;

Triple: bxy; -4b squared y; a to the 3rd power;

Four times: 3 x to the power of 3a; -b squared x squared. 1 2axy squared.

8. From the question, we know that the coefficient of the mononomial cannot be zero, so m-2 is not equal to zero, and m is not equal to 2;

n+4=5 calculates n=1

Therefore, the answer is D9, and there may be three cases for this monomial, which are:

2 3xyz to the third power; -2 3xy squared z squared; -2 3xy to the 3rd power z

Question 3: Set the time it takes to return to the student y, and the total distance x

5y+5+x=the second question: X in A, y in B.

x+y=20

28+x=2（18+y）

y=4，x=16

Question 1: Set the original price xx=

1. Solution: Set the original price of each refrigerator at X yuan.

x+40%x）x80%=2270

2. Solution: If x people should be transferred to place A, then person 2x should be transferred to place B.

I'm only in elementary school and junior high school, and I don't know how to do it yet, so it's better to do it myself.