There are two identical rectangles 10 decimeters long. Put them together into a large rectangle with the shortest circumference. How many centimeters is the circumference of this rectangle? Two together?

There are two identical rectangles 10 decimeters long. Put them together into a large rectangle with the shortest circumference. How many centimeters is the circumference of this rectangle? Two together?

The sum of the circumference of two rectangles is 60 decimeters. If the two sides of 10 decimeters are aligned, then the circumference of the two rectangles is reduced by 10 * 2 = 20, and the result is 40 decimeters. But this is a square. If we consider that a square is a special case of a rectangle, the answer is 40 decimeters, which is 400 centimeters. If a square can't, then

What is the formula for calculating the circumference of a circle and the volume of a cylinder?

Circumference of circle = 2 × π × radius = π × diameter
Volume of cylinder = area of bottom × height = 2 × π × radius × height

Solution equation: radical x-radical (5-x) = 1

√x-1 = √(5-x)
Square on both sides
x-2√x+1 = 5-x
2x-2√x-4=0
x-√x-2=0
(√x+1)(√x-2)=0
√x=2
x=4
In addition, this kind of problem added square or root sign without authorization, because it is possible to introduce pseudo root or virtual root with "±". After solving, it is better to replace all roots to check

How to do the X-Y power of Y '= e, find the differential,

Solve differential equations
y'=e^(x-y)
dy/dx=e^x/e^y
e^ydy=e^xdx
e^y=e^x+c
y=ln(e^x+c)

What are the literal expressions of all chemical reactions in unit 1 and 2 of chemistry grade 9 Volume 1?
If you have a good answer, add 50 minutes

Magnesium burns in air: 2mg + O2 ignites 2MgO 2, iron burns in oxygen: 3Fe + 2O2 ignites fe3o43, aluminum burns in air: 4Al + 3O2 ignites 2al2o34, hydrogen burns in air: 2h2 + O2 ignites 2h2o5, red phosphorus burns in air

How to calculate the addition, subtraction, multiplication and division of 1 6, 1 8, 1 9 and 1 10 equal to 24

If Y1 < Y2, then the value range of X is:______ ．

Y1 ＜ Y2, that is, 3x-4 ＜ 3-x, the solution is: X ＜ 74. The value range of X is: X ＜ 74

The perimeter of a circular fountain is 12.56 meters. How many square meters does the fountain cover?

Analysis: use the circle perimeter formula to calculate radius, and then calculate the area according to the circle area formula
3.14×（12.56÷3.14÷2）2,
=3.14×4,
=56 (square meters);
A: it covers an area of 12.56 square meters
Comments: this question mainly examines the use of the circumference formula and area formula of a circle

5. 5, 1, 5 count as 24

1. Routine method
5*(5-1/5)
2. Several special operations
(5-5/5*1)!=4!=4*3*2*1=24
(5-1*5/5)!1*(5-5/5)!
(5-1)!*5/5 5!/(5+5mod1)=5!/(5+0)
√5 * √5 *5-1

Find the curvature of ellipse 4x ^ 2 + y ^ 2 = 4 at point (0,2)

Curvature k = | y '' / (1 + y ` 2) ^ (3 / 2)|
Y = f (x) denotes the functional equation, y 'is the second derivative and y' is the first derivative
4X ^ 2 + y ^ 2 = 4 is an implicit function, but it's because as long as (0,2) can write the explicit function of this section