A few math problems Urgent! 15

Question 1: a 2x3xm, b 3x5xm (m is a natural number, and m is not equal to 0), if the greatest common divisor of a and b is 21, then m is (7), and the least common multiple of a and b is (210).

Question 2: c (you can try algebra) (e.g. let r=3, h=6) Question 3: Solution: Let the person who likes to eat apples the most be x.

x+13 20x+13 20(1+5 13)x=17x3 x=20 then 13 20x=13 13 20(1+5 13)x=18

Answer; There are 13, 20 and 18 people who like bananas, apples and oranges the most.

Question 4: Solution: There are 8x people in the original first class and 7x people in the original second class.

8x-8) (7x+8)=4 5 (parentheses to indicate that it is a whole) 5x(8x-8)=4x(7x+8) (x for multiplication) x=6 then 8x=48 7x=42

A: There were 48 students in the original first class and 42 people in the original second class.

1. There is no natural number m that fits the topic

2. C3, set the person who likes to eat apples the most as x

x+13 20*x+13 20*(1+5 13)*x=17*3x=20 Banana 13 people, Apple 20 people, Orange 18 people.

6. There are x people in a class.

x-4):(7/8*x+4)=4:5

x = 24 24 people in the first shift, 21 people in the second shift.

1. A, B, and C bought a total of 8 loaves of bread and ate them equally, A paid for 5 loaves of bread, B paid for 3 loaves of bread, and C did not bring any money. After calculation, C should pay $4, how much should A get back?

Answer] 8 loaves of bread are 4 3 12 yuan, each loaf is 12 8 yuan, A paid 5 yuan, and should be recovered.

2. The other conical container is 21 cm high, and the container is filled with water. If all the water is put into a cylindrical container with an equal bottom and a 20 cm notice, then the water is ( ) cm high.

Answer] is actually to turn a cone into a cylinder with equal bottom, the height is 1 3 of the cone, so the height of the water is 21 3 7 cm.

3. If the height of the trapezoid is 6 cm and the median line is 5 cm, then the area of the trapezoid is ( ) square centimeters?

Answer] The area of the trapezoid can be the median line height, then the area of the trapezoid is 5 6 30 square centimeters.

4. The ratio of the two kinds of upper flat ** is 7:3. If their **all**70 yuan, their **ratio is 7:4. It turns out that how many yuan are the ** of these two kinds of Shangping?

Answer] Since **are**70 yuan, then the difference between the two ** is the same, and the multiplication method can be used to solve the problem, so that the number of copies is the same.

then 7 copies were added, indicating that each copy was 70 7 10 yuan.

It turned out that A was 10 21 210 yuan, and B 10 9 90 yuan.

1.Each person ate 8 3 loaves of bread, so each loaf of bread (8 3) 4 = 2 3 yuan A overpaid 5-8 3 = 7 3 loaves of bread so it should be recovered (7 3) * (2 3) = 14 9 yuan.

2.Because the volume of the conic = 1 3 volume of the cylinder, the water height can be known to be 1 3 * 21 = 7 cm

3.The area is 5*2*6 2=30

4.Let the original ** of A be x and the original ** of B be y

x/y=7/3

x+70/y+70=7/4

x=210, y=90

1. A should take back the yuan.

Centimeter. 4. The original price of A is 210 yuan and B is 90 yuan.

1.The price of each loaf is 4 (8 3) = yuan, and A should **27 The volume of the conic is 1 3 of the cylinder, 21 3 = 73The 30 median line is half of the upper bottom + lower bottom.

4.A: 210 B: 90 Let A be 7x and B be 3x. Get (7x+70) (3x+70)=7 4 to solve the equation.

1.Solution: Everyone can eat 8 3 loaves of bread, C needs to pay 4 yuan, one loaf of bread is yuan, A should pay 4 yuan, but actually paid yuan, so the yuan should be recovered.

Answer; 2.Solution: (7 cm).

Volume of the cone = sh3 Volume of the cylinder = sh3Solution: median line = (upper bottom + lower bottom) 2, so: the area of the trapezoid = 6 * 5 = 30 cm 2

4.Solution: Let the ** of A be 7x yuan, and the ** of B be 3x yuan 4 (7x + 70) = 7 (3x + 70).

x=30A: ......

ⅰ。4 3 = 12 (yuan) This is the money of eight loaves of bread.

12 8 = yuan) This is the money of bread.

$5) This is the money paid by A.

Meta) is the answer.

The bottom area is all s, and the water height is h

1／3×s×21=s×h

h=7cm.5 2 = 10 (cm) is the trapezoidal upper bottom plus lower bottom and 10 6 2 = 30 (square centimeters) This is the answer.

Let A's ** be 7x and B's ** be 3x

7x＋70）÷（3x＋70)=7／4

x=307x=210 3x=90 Here's the answer.

1.A should take back the yuan.

centimeters square centimeters.

4.A210 B90

Solution:1Each man ate 2 3 loaves, B paid 1 3 loaves of bread more, and A paid 7 3 loaves of bread more.

Divide 4 to 7:1. So, A deserves the yuan.

Cone = 1 3sh, h = 21 cm, i.e. v cone = 7s cubic centimeter. V-pillar = sh, i.e. 7s = sh, so h = 7 cm.

3.Trapezoidal median line = 1 2 (upper bottom + lower bottom), S ladder = 1 2 (upper bottom + lower bottom) h = 5 times 6 = 30

4.Let A be 7x and B be 3xIt can be listed by the title.

7x+70)：（3x+70)=7:4

The solution is x=30, so A is 210 yuan, and B is 90 yuan.

1.There are x number of students.

3x+3=4x-2 gives x=5

There are 5 classmates and 18 trees.

2.There are y people, excluding the total score of the miscalculated student, (x+89)=;

x+98）=；

From the above 2 equations, we can get y=4530 days.

1. There are a total of x students.

then 3x+3=4x-2

x=53x+3=18

A: There are 5 students and 18 trees.

7) A: There are 35 students.

3. According to this law, we can find that after the nth day, the potion still has the original 1 2 2 3 3 4 ......n-1)/n=1/n

So on the 30th day, after evaporation, the potion still has 1 30 left

You don't have a ruler source number since you are sleepy!!

1 2 --4, you can wait for 16 x = -4

2 b is not equal to 0, so a is not equal to 0, so the wheel of honor is 10a=a+10 in the calculation of a=9 points, only 10, no way, difficult.