Math problems, master solving! Solve a math problem!

Set up x yuan. For every price increase, 10 pieces are sold less.

Therefore, the number of pieces sold is the original number of pieces, minus the price increase, and the number of pieces sold is less.

200-10*x pcs.

The profit of each piece is (10+x-8) yuan.

So the equation can be columnized as.

10+x-8）*（200-10*x/

This is a practical problem solved with the knowledge of one-dimensional quadratic equations in the first grade of junior high school, and the "xx" in the following solution process is "the square of x".

Solution: After setting the price increase x times, the daily profit is 640 yuan.

400－20x+100x－5xx＝640

80x－5xx＝240

5xx－80x+240＝0

xx－16x+64＝0

x－4）×（x－12）＝0

Solution: x 4, the price is 10+4 yuan.

or x 12, the price is 10+12 RMB.

A: When the price is 12 or 16 yuan, the profit per day is 640 yuan.

Set the price at $x, then.

The profit per piece is: x - 8 yuan.

The sales volume per day is: 200 - x - 10) 10 = 20 x pieces.

The total profit per day is: the profit earned per piece sold per day.

x - 8 ）20x = 640

Set a price increase.

10+ gives x=12

So the price is set at 10+ yuan.

1: Let's explain it in layman's terms

The speed ratio of passenger and truck is 6:5, that is, the bus runs 6 kilometers, the truck runs 5 kilometers, the passenger car runs 60 kilometers, the truck runs 50 kilometers, the passenger car runs 120 kilometers, and the truck runs 100 kilometers.

The bus arrived at the station at 120 kilometers, and the truck still had 20 kilometers to run, and the 20 kilometers took the truck half an hour to finish, so the truck speed was 40 kilometers per hour.

The speed of the bus is 40, 5, 6, 48 km / h.

Solution: Let the speed of the passenger car be 6x, and the speed of the truck is 5x, there are:

120÷5x＝120÷6x＋

x＝（24－20）×2＝8km/h

The speed of the passenger car is 8 6 48 km h, and the speed of the truck is 8 5 40 km h2: this rectangle has two opposite sides (two long sides) that are approximately straight lines formed by the outer circle of the circle, which are actually small arcs one by one, and the other two sides are the length of the fan, that is, the radius.

The extra 8 cm is the length of the two radii, and the radius r is 4 cm. The area is.

1. Set the speed of the passenger car 6x and the speed of the truck 5x

120/6x=120/

x = 8 kmh.

Truck speed = 5x = 40 km/h.

2. The perimeter of the approximate rectangle is composed of the circumference of the original circle (2 long sides of the approximate rectangle) plus 2 radius lengths (2 wide sides of the approximate rectangle), so the 8 cm that the circumference of the approximate rectangle increases from the circle is the radius of the circle*2. From this, we can see that the radius of the circle is r=4cm.

s = square centimeter.

1 Let the speed of the truck be x, then by the title, the speed of the passenger car is 6 5x.

Trucks spend more hours than buses. Get: 120 6 5x + equivalent to 100 x + i.e. x=40

A: The speed of the truck is 40 kilometers per hour.

2Is it necessary for a process?

The answer is 16

1.Solution: Set the speed of the passenger car to 6x, the speed of the truck to 5x

120÷6x=120÷

x = 8 when the truck speed is 5x = 40km.

2: This rectangle has two opposite sides (two long sides) that are approximately straight lines formed by the outer circle of the circle, which are actually small arcs one by one, and the other two sides are both fan-shaped lengths, that is, radius.

The extra 8 cm is the length of the two radii, and the radius r is 4 cm. The area is.

The height of the cylinder = the diameter of the base garden = 10 * 2 = 20 cm.

The volume of the cylinder = * 20 = 6280 cubic centimeters.

The bottom area is r 2, the cylindrical height is flat 2 r, and the cylindrical volume r is 2*2 r=2 2r 3=2000 2

The cylinder is higher than the width of the cut rectangle.

10*2=20(cm)10^*

When you go to the math know-it-all questions, it's all professional teachers who are solving the problems. Accurate.

The base area is multiplied by the volume so.

The radius of the circle is multiplied by 2 to get the width of the rectangle.

Multiply the radius of the circle by 2 to get the diameter of the circle, and later calculate it yourself- -

The middle rectangle is the side part of the cylinder, and it is easy to know that the height of the side is the width of the rectangle, that is, the diameter of the garden, that is, 20 cm!

v=s*h=

As can be seen from the diagram, the length of the truncated rectangle is the circumference of the truncated circle, and the width is the diameter of the truncated circle (because it is just enough to make a cylinder).

So the height of the resulting cylinder is the diameter of the circle.

The volume is the base area multiplied by the height as r r= r

The length of the rectangle is 20, the radius of the cylinder is 10, and the bottom area x height is the volume of the cylinder.

That is, 100 x20 = 2000 *2

W>2, X+Y+Z>=3,3<=W<=17, W has 15 possibilities, when W=17, X+Y+Z=3, there is only one possibility, when W=16, X+Y+Z=4, one of which is equal to 2, there are three possibilities, and the conclusion can be obtained by this deduction.

Demover's theorem and Euler's formula "E i = cos + isin = 2 (cos30°+isin30°) (cos60°+isin60°) (cos45°+isin45°)."

2(cos90°+isin90°)/(cos45°+isin45°)

2(cos45°+isin45°)

2（1+i）

Trunk section radius:

Centimeter. Cross-sectional area: square centimeters.

The annular area is equal to the outer circle area minus the inner circle area and is:

Square metre.

First of all, the first one asks.

Circumference c= *2*r= (r is the radius of the tree, and r=20cm.)

So the cross-sectional area s=r2*

The solution is s=1256cm2

Then the second asked.

Ring area = outer circle area - inner circle area.

Therefore, the area of the torus s=r2* -r2* r is the radius of the outer circle, and r is the radius of the inner circle) is solved to obtain s= (the result after keeping two decimal places).

We use the method of equations to solve, which is easy to understand

1。The original length of the packaging rope is x meters, and the equation can be obtained with the title.

x(1-1/5)(1-3/4)=2

Solution: x=10

2.The speed of the wagon is 56*(6 7)=48

Due to distance = speed * time.

Therefore, the distance between A and B = 48 * (14 3) = 224 is 224 kilometers apart.

15 Ah. Calculate the height first. Then subtract the area of the right triangle from the total area.

Yuan. Tops 88 yuan.

Ton. 12 4 * 25 = 75 tons.

The original grain was 75 tons.