A pyramid geometry is composed of several cubes, and the construction method is as shown in the figure. The four vertices of the lower bottom surface of the upper cube are the midpoint of each side of the upper bottom surface of the lower cube. It is known that the edge length of the lowest cube is 2, and the surface area of the pyramid (including the bottom area of the lowest cube) is more than 39, then the number of cubes in the pyramid is at least () A. 4B. 5C. 6D. 7

A pyramid geometry is composed of several cubes, and the construction method is as shown in the figure. The four vertices of the lower bottom surface of the upper cube are the midpoint of each side of the upper bottom surface of the lower cube. It is known that the edge length of the lowest cube is 2, and the surface area of the pyramid (including the bottom area of the lowest cube) is more than 39, then the number of cubes in the pyramid is at least () A. 4B. 5C. 6D. 7

The surface area of the bottom cube is 24; the edge length of the second layer cube is 2 × 22, and the area of each face is 4 × (12); the edge length of the third layer cube is 2 × (22) 2, and the area of each face is 4 × (12) 2; the edge length of the n-layer cube is 2 × (22) n − 1, and the area of each face is 4 × (12) n − 1; if the tower is n-layer

A tower geometry is composed of several cubes, as shown in the figure. The four vertices of the bottom surface of the upper cube are just the midpoint of the upper surface of the lower cube. It is known that the edge length of the uppermost cube is 1. And the total area of the tower geometry [excluding overlapping parts, including the bottom area of the lowest cube] is equal to 76, then how many cubes are there in the tower geometry

Four

Use five small cubes to form a three-dimensional figure on the desktop. How to place the surface of the small cubes so that they are exposed to the outside? How to place the surfaces of the small cubes so that they can expose 18 surfaces? Which kind of pendulum has the least area exposed to the outside? How to place the surfaces exposed to the outside most?

The feature of a cuboid is that it has 12 edges, 6 faces and 8 corners. Each corner is a 90 degree cube. The feature of a cuboid is that a cuboid with six equal faces is a cube. The surface area of a cube is the sum of the areas of six identical faces of a cuboid

(1) if the object is placed in three layers, try to find the surface area of the object; (2) by analogy, if the object is placed in 20 layers, find the surface area of the object

(1) 6 × (1 + 2 + 3) · A2 = 36a2, so the surface area of the object is 36a2; (2) 6 × (1 + 2 + 3 +) +20) The surface area of the object is 1260a2

Help to solve the problem of polynomial and factorization in Grade 7, thank you
The common factor of polynomial: - x2-9 and X2 + 6x + 9 is = () factorization factor: - x2 + y2 = = ()
2.25x2-0.25y2==( ) 1-x+0.25x2==( )

-(x^2-9)=-(x-3)(x+3)
x^2+6x+9=(x+3)^2
So their common factor is x + 3
Factorization:
one
-x^2+y^2
=-(x^2-y^2)
=-(x-y)(x+y)
two
25x^2-0.25y^2
=25x^2-(25/100)y^2
=25x^2-(1/4)y^2
=(1/4)(100x^2-y^2)
=(1/4)(10x-y)(10x+y)
three
1-x+0.25x^2=(0.5x-1)^2

How to factorize a polynomial easily

Square of factoring factor 4m-n-4m + 1
Use the square of formula a + the square of B + the square of C + 2Ab + 2Ac + 2BC = (a + B + C) to factorize the following formulas:
1. The square of X + the square of 4Y + the bungalow of 9z-4xy + 6xz-12yz
2. Square of X + square of 4Y + bungalow of 9z + 4xy-6xz-12yz
3. The square of X + the square of 4Y + the bungalow of 9z-4xy-6xz + 12yz

x^2+4y^2+9z^2-4xy+6xz-12yz=(x-2y+3z)^2
x^2+4y^2+9z^2+4xy-6xz-12yz=(x+2y-3z)^2
x^2+4y^2+9z^2-4xy-6xz+12yz=(x-2y-3z)^2

Find the factorization detailed explanation, the square of x minus 2mx plus x plus 4m minus six

x^2 - 2mx + x + 4m -6
= x^2 - 2mx + m^2 - m^2 + x + 4m -6
= (x - m)^2 - m^2 + x + 4m -6
= (x - m)^2 - (m^2 - 4m + 4) + x - 2
= (x - m)^2 - (m - 2)^2 + x - 2
= (x - m + m - 2)(x - m - m + 2) + x - 2
= (x - 2)(x - 2m + 2) + x - 2
= (x - 2)(x - 2m + 3)

Factorization of (a minus b) (a plus B minus 1) plus a minus B
Such as the title

(a minus b) (a plus B minus 1) plus a minus B
=(a-b)(a+b-1)+(a-b)
=(a-b)(a+b-1+1)
=(a-b)(a+b)

How to factorize the quintic addition of x minus 1?

=x^5+x^2-x^2+x-1
=X^2(x^3+1)-(X^2-x+1)
=x^2(x+1)(X^2-x+1)-(X^2-x+1)
=(X^2-x+1)(x^3+x^2-1)