Find 40 simple math problems for the first year of junior high school

Uh, the question indicates that there is a weak heart.

The first question, the number of rooms in the costume is x:

4x+13=5(x+1)

x=8 Second Hall Mitigation:

The length of the passenger car is 150m, and the length of the truck is 250mIf the two cars are moving in the opposite direction, then it takes a total of 10s from the front of the two cars to meet the rear of the car, and the speed of the two cars is 40m s

Then, if the passenger car is x, then:

100*x-（40-x）*100=150+250x=22

Set the minimum side vertical void to x and match.

The maximum side is 3x

And the sum of the two sides is greater than the third Yu Chang burning side.

That is, the length of the other side is greater than 2x and less than 3x.

100 is greater than 6x and less than rapid 7x

You can get x for.

If at least x is answered correctly, then 16-1-x=15-x is answered incorrectly, and 6x-2(15-x) 60 is answered

8x≥90x≥

Here we should use the method of destroying Huai, then x=12

Therefore, this student can answer 12 questions correctly in order to win the award.

1.The inverse of the original formula =3*(4 3)-4 2=4-2=2 2 is -22The inverse of the original formula =3*(-3 2)-2 2=-9 2-1=-11 2 -11 2 is 11 2

3.When a 0.

Original formula = 3 a - -6a 2=-3a+3a=0 when a = 0.

Original formula = 3 a - -6a 2 = 0 - 0 = 0 when a 0.

Original formula = 3 a - -6a 2 = 3a - 3a = 0

From the meaning of the title, the denominator is: 1 squared + 1, 2 squared - 1, 3 squared + 1, 4 squared - 1 ,......

According to this rule, the denominator of the 20th number is 20 squared -1, so the 20th number is 1 399

Solution: x3=2x3 2, and then Ti3 2

2. The first two combinations are to the n+1 power of 2, and the multiplication operation of the same base power is used, and then the merger is used with the later ones.

3. 3m power of a = 3rd power of m power of a, substitution is 2 to the 3rd power = 8, 2n power of a = 2nd power of a, substitution is 3 to the 2nd power = 9, the result is 72

Coarse candles are the same length as thin candles, coarse candles can be lit for 5h, thin candles can be lit for 4h, if these two candles are lit at the same time, after a period of time, the remaining coarse candles are 3 times that of thin candles, ask how long have these two candles been lit?

Let the total length be in unit "1" and the time be x

1-x/5=3[1-x/4]

x=40/11

i.e. lit for 40 to 11 hours.

Three children share a bag of candy, the first one gets half of the total number and one more piece, the second one gets the remaining 1 3, and the third finds that his candy is exactly twice as much as the second person, and asks what is the total number of candies?

Let the total number be xx 2+1+[x 2-1]*1 3+[x 2-1]*2 3=xx=The question seems to be wrong.

A farm worker hoes grass on two plots of land, the larger one twice as large as the smaller one. In the morning, the workers are hoeing on the large patch, and in the afternoon the workers are separated in half, and half of them are still left on the large ground to hoe, and the grass is finished in the evening; Another worker went to the small field to hoe the weeds, and by the evening there was still some left, and another worker went to hoe another day, and the hoeing was done in exactly one day. How many workers does this farm have?

Assuming that the total number of people is x, the daily workload of one person is unit "1".

The area of the large plot = 2 * the area of the small plot.

x*1 2+x 2*1 2=2[x 2*1 2+1]x=8, i.e. a total of 8 people.

4. If A increases x% to get B, and B decreases y% to get A, then the relationship between X and Y is (c)a[1+x%]=b====>1+x%=b ab[1-y%]=a====>1-y%=a b[1+x%][1-y%]=b a*a b=11-y%+x%-x%y%=1

y+x-x*y%=0

x[1-y%]=y

x=y/[1-y%]=100y/[100-y]

1.6 3 7 3 to the fifth power.

2 3 2 7 3 to the fifth power.

2.2 to the nth power + 2 to the nth power - 3 2 to the n + 1st power = 2*2 n-3*2 (n+1).

2^(+1)n-3*2^(n+1)

2*2^(n+1)

2^(n+2)

a^n=3，a^(3m+2n)=a^3m/a^2n=2^3/3^2=8/9

Solution: 21 hours and 23 minutes ===

Approximately equal to the incompleteness of your question, if you are flying at a speed of 3 m per second then this is the answer.