Math problems for the first year of junior high school 2 questions! 20 points

Set: It turns out that there are x people.

1/3x+4 = 1/2x

1/6x = -4

x = 24

I'm also in my first year of junior high school, and I ask each other for advice, thanks

Question 1: Solution: There are x people in this math group.

1/3x+4=1/2x

Solution: x=24

A: There were originally 24 people in this math group.

1) Because the number of girls has increased from 1 3 to 1 2, there are more girls in these four classmates, 4 girls or 3 girls and 1 boy.

4 Female: Original x person: (x 4+4) (x+4) = 1 2, x = 81 3 * x + 4 = 1 2 * x x = 24

3 women and 1 man: (x 4+3) (x+4)=1 2, x=42) over 10 cubic meters, the water price is.

10 to 20, the water price is 3*10=30

70-30-26), plus 24 cubic meters.

Let the water use x, column segmentation function.

f(x)= （0《x<10）

26+3(x-10) (10《x<20)

56+ (x》20)

1 3 = 2 6, after 4 classmates came, it was 3 6, originally-now = 1 serving. 1 is 4It turns out to be six copies, 4x6=24

1. b>c>a>d>e

2.After 10 times, it is 1 (2 10) = 1 1024 mm m = mm

After 20 times it is 1 (2 20) = 1 1048576 m = nanometer.

(1) d e b c a (2) 1 1024 (m, ) 1 2 20 (m) after the twentieth pass

2A square x27b square xc=54 and abc is a natural number, then b is set as 1 then 2a square xc=2 analysis shows a=c=1, that is, it is true (1-1-1)2005 square =-1

1998 is an even number, and only 2 in the formula can multiply an even number, so now we will take 1998 2=999, then we can find that a can only be 1, and then look at the single digit of 999 is 9, and there are 27 and 37 digits left in the equation multiplied by 9, and you will think of multiplying 27 and 37, and you will find that it is exactly 999 1998 2=999 27*37=999 a=1 b=1 c=1 like this (...)There will only be 1 -1 0 +2 -2 in the power () of the very large power You can guess it It's not very good at typing to give points !!

According to the title, 2 a*27 b*37*c=1998 2 a*27 b*c=1998 37=54 2 (a)*3 (3b)*c = 54 Since the power of 2 is an even number, it can be assumed that a=1, b=1, c=1 can be assumed according to 2*27=54

Bring in the original formula: 2 (1)*3 (3)*1= 54 match. So a=1, b=1, c=1

a-b-c)^2005 = （1-1-1)^2005 =（-1)^2005= -1

Solution: After the opening of the through train, the city's tourism company will travel to the "Shaoyang-Shanghai" line.

3x+400=5/6*4x

18x+2400=20x

2x=2400

x=1200

So x (5 6) = 1200 * 5 6 = 1000 (yuan) Answer: Before the opening of the through train, the city's tourism company for the "Shaoyang-Shanghai" line tourism ** is 1000 yuan, after the opening of 1200 yuan.

I'll admit I'm here to do the task, sorry.

|To find the number, there must be a complete process ps: first turn the minus sign into a plus sign!

2 3-1 8 (4 2 3 is 4 and 2/3) The requirements are the same as above.

If |a|=3,|b|=1,|c|=5, and |a+b|=a+b,|a+c|=-a+c), find the value of a-b+c. (Equations are required).

a|=3,|b|=1,|c|=5

then a = 3, b = 1, c = 5

It is also known |a+b|=a+b,|a+c|=-a+c), so a=3, b=1, c=-5

a-b+c=3+1-5=-1

or a-b+c=3-1-5=-3

1/2-1|+|1/3-1/2|+|1/4-1/3|+.1/2010-1/2009|..Find the number (equation).

1. Set time x minutes.

100*60*x=90*75*16

The road must be long.

2.Let the distance be xm

x=60*1+a

The classmate walked one more team leader than honestly following the back of the line.

3. Let the flow rate be xkm h

120/4-120/5=2x

x=3 downstream velocity minus reverse velocity is equivalent to twice the velocity of the water after the ship speed is offset.

m+n power.

2) to the m+n power.

2) to the m+n power.

2 to the m power 2 to the n power).

A b 2 to the power of m + n + 2 to the power of 3 m + 2 to the power of 2.

2 to the power of m, 2 to the nth power) + (2 to the 3m power, 2 to the 2n power) = ab + (2 to the m power) 2 to the nth power) = ab + a b

So 2 to the power of a, 2 to the power of b, = 2 to the power of c.

2 to the power of a + b = 2 to the power of c.

So a+b=c