There are six same cylindrical columns in the hall, each of which is 8 meters high and 2.4 meters long. Each kilogram of paint can be painted for 4.5 square meters. Painting these columns requires painting

There are six same cylindrical columns in the hall, each of which is 8 meters high and 2.4 meters long. Each kilogram of paint can be painted for 4.5 square meters. Painting these columns requires painting

8 * 2.4 * 6 / 4.5 = 25.6kg (the cylinder is a rectangle with a length of 6m and a width of 2.4m.)
A: it takes 25.6kg to paint these columns

Four nines with proper operation symbols and brackets are equal to seven

9-(9+9)/9

How many zeros of the function f (x) = 2 to the x power + X-2?

It is easy to get that f (x) is an increasing function on R,
And f (0) = - 10
Thus f (x) has and has only one zero point, and is in the interval (0,1)

Given that a and B are opposite numbers, C and D are reciprocal, the absolute value of X is equal to twice of its opposite number, find the value of X3 + abcdx + A + BCD

It is known that a and B are opposite numbers, that is, a + B = 0
C. D is reciprocal to each other, i.e. CD = 1
If the absolute value of X is equal to twice of its opposite number, that is, | x | = - 2x, then x = 0
The value of X3 + abcdx + A + BCD
=0+0+A+B
=0

The seven halves are equal to 10, no matter how they are added, subtracted, multiplied, divided or bracketed

1 / 2 uses 0.5 to show that it looks better. There are many ways
（（0.5+0.5）/0.5/0.5+0.5/0.5）/0.5

According to the image or property of the function y = 3x-15, when determining the value of X: (1) y > 0; (2) y < 0

Let 3x-15 = 0, the solution is x = 5, k = 3 ＞ 0 in the ∵ function y = 3x-15, y increases with the increase of X, and (1) when x ＞ 5, y ＞ 0; (2) when x ＜ 5, y ＜ 0

When the height of a cuboid is increased by 5 meters, it becomes a cube, and its surface area is increased by 160 square meters. The volume of the original cuboid is () cubic meters. The largest surface is surrounded by () and (), and the smallest surface has () faces

The area of the four sides is equal to the perimeter of the bottom * the height
So the perimeter of the bottom surface * 5 = 160
If the perimeter of the bottom is 32 and the ground is square, the side length of the square is 32 / 4 = 8m
Original height = 8cm-5cm = 3cm
The volume of the original cuboid is 3 * 8 * 8 = 192 cubic meters
The largest area is surrounded by (bottom surface) and (top surface), and the smallest is surrounded by (4) sides

7,9,11,13 are 24 points! 10,8,6,4 are 24 points,

I only know the second one, 10-6 = 4, 4 * 4 = 16, 16 + 8 = 24

X = ACOS cubic t y = asin cubic t a is constant T is angle derivative

x=a(cost)^3,
y=a(sint)^3
that
dx/dt= -3a(cost)^2 *sint
dy/dt=3a(sint)^2 *cost
that
dy/dx
=(dy/dt) / (dx/dt)
=[3a(sint)^2 *cost] / [-3a(cost)^2 *sint]
= -tant

When a solid ball is put into water, the buoyancy is 10N. When it is put into alcohol (density 800kg / m ^ 3), the buoyancy is 9N

The buoyancy of the object in the liquid is not greater than its own gravity. Because the buoyancy of the small ball in the alcohol is less than that in the water, it can be judged that the buoyancy of the small ball in the alcohol is less than that in the gravity, so it is in the submerged state. The volume of the arranged alcohol is equal to the volume of the small ball. According to Archimedes' principle, the buoyancy 9N is divided by G = 9.8n/kg