A 24 cm long rectangular iron sheet is welded into a box without a cover by subtracting a small square with a side length of 3 cm from its four corners. The volume of the box is 486 cubic centimeters That's a good answer Take a 24 cm long rectangular iron sheet, subtract the small square with side length of 3 cm from the four corners, and then weld it into a box without cover. The volume of the box is 486 cubic cm. Calculate the volume of the original rectangle

A 24 cm long rectangular iron sheet is welded into a box without a cover by subtracting a small square with a side length of 3 cm from its four corners. The volume of the box is 486 cubic centimeters That's a good answer Take a 24 cm long rectangular iron sheet, subtract the small square with side length of 3 cm from the four corners, and then weld it into a box without cover. The volume of the box is 486 cubic cm. Calculate the volume of the original rectangle

Length of uncovered box = 24-2 × 3 = 18 cm
Height of open box = 3cm
Box volume = l × w × H = 18 × w × 3 = 486 CC
Width of open box = 486 / 54 = 9cm
The width of the original rectangle is 9 + 2 × 3 = 15 cm
The area of the original rectangular iron sheet is 24 × 15 = 360 square centimeters

16 cm wide rectangular sheet iron, cut out 4 cm long square on the four corners and weld it into a box without cover. The volume of the box is 320 cubic cm, and the original area is

Let length x, V-Body = (16-4-4) × 4 × (x-4-4) = 320, and the solution is x = 18, s area = 18 × 16 = 288cm

A and B start from a and B at the same time. When they meet, car a walks 18 kilometers less than car B. after meeting, car a arrives at place B in 1 hour and 21 minutes, and car B arrives at place a in 36 minutes. The speed of car a and B and the distance between two places are discussed

A. B distance between two places 2S, 1 hour, 21 minutes = 27 / 20 hours, 36 minutes = 12 / 30 hours, speed ratio of a and B: (S-9): (s + 9) speed ratio after meeting: [20 (s + 9) / 27]: [20 (S-9) / 12] so: (S-9) / (s + 9) = [20 (s + 9) / 27] / [20 (S-9) / 12] (s + 9) ^ 2 / 9 = (S-9) ^ 2 / 45s ^ 2-18 * 13s + 81

If the distance from the moving point m (x, y) to the point F (4,0) is 1 less than the distance to the straight line x + 5 = 0, then the trajectory equation of the point m is?
Why is the distance from the moving point m (x, y) to the straight line x + 5 = 0 | x + 5 |?
Shouldn't we use the distance from point to line?

Because x + 5 = 0 linear x = - 5A.. it is perpendicular to the X axis, then the distance from the point to him is only related to the abscissa. That is X - (- 5). The absolute value is added because it is the distance and can only be positive. When x is less than - 5, X - (- 5) may be negative, so the absolute value is added to ensure that it is positive
The general method is (｜ x + 5-1) & sup2; = (x-4) & sup2; + Y & sup2;
(originally, it should be square to the right, but in order to simplify the calculation, we should square both sides at the same time.)
It can be discussed that when x is less than - 5, it can not satisfy that the distance to point F is smaller than the distance to the straight line, so the absolute value can be removed to solve the problem
The function problem draws the picture, is advantageous to the solution

How to change the equation (x + 2) (X-2) = 3x & # 178; - X-5 into a general form?

That is, X & # 178; - 4 = 3x & # 178; - X-5
2x²-x-1=0

What are the top three countries with the largest land area, the largest population and the largest population density in the world?

Land area: Russia, Canada, China
Population: China, India, USA
Population density: Vatican, Bangladesh, Japan

What determines K in Coulomb's law

This k is a constant determined at the time of the cosmic explosion. It's the same as the speed of light, Pai, G and so on
Of course, if you ask how to measure, then it is through the torsion scale experiment!

September 1st, 2006 is Friday. What day is October 1st, 2006? New Year's day, 2007
September 1st, 2006 is Friday. What day is October 1st, 2006? What year is 2007
September 1, 2006 is Friday. What day is October 1st, 2006? What about 2007? Who is fast and good? Who do I give to.

30 divided by 7 = 4... 2
(30 + 30 + 31) divided by 7 = 13. Monday

Mathematics knowledge and stories (about 30 words)
Not too much, I have to do color a, thank you
There is not much time

One day, a vegetable buyer bought carrots at the market. One kilo of carrots cost 5 yuan. Another wanted to buy 8 kilos. He didn't know how much it would cost

(1 / 143 + 1 / 77 + 1 / 91) divided by (20 / 99 + 1 / 9) - 2 / 91 =? Please use simple calculation!
(1 / 143 + 1 / 77 + 1 / 91) divided by (20 / 99 + 1 / 9) - 2 / 91 =? Please use simple calculation! Division, not division!

(1/143 + 1/77 + 1/91) / (20/99 + 1/9) - 2/91
= (1/143 + 1/77 + 1/91) / (31/99) - 2/91
= (9/13 + 9/7 + 99/91) / 31 - 2/91
= (63/91 + 117/91 + 99/91) / 31 - 2/91
= (279/91) / 31 - 2/91
= 9/91 - 2/91
= 7/91
= 1/13