7: 8 = 8 / 8 () = 35 divided by () = 21: () = 72 ()

7: 8 = 8 / 8 () = 35 divided by () = 21: () = 72 ()

7: 8 = 7 / 8 = 35 divided by (40) = 21: (24) = 63 / 72

What is the quotient of 5 / 7 of 35 divided by 42 3 / 8?

(35X5/7)÷(42X3/8)
=25÷(63/4)
=25X(4/63)
=100/63
=1.5873015873015873015873015873016.

18×(10/33÷2)
The answer is 18 and 5 / 33

18×(10/33÷2)
=18×(10/33×1/2)
=18×5/33
=90/33
=30/11
=2 and 8 / 11
From the calculation point of view, the original question should be 18 + (10 / 33 △ 2)
It must be plus, not multiply. The result is what you say

As shown in the picture is a rectangular grassland, 16 meters long and 12 meters wide, with a road 2 meters wide in the middle. Calculate the area of grassland (shadow part)

The total length of the road is (16 + 12-2) meters, that is 26 meters. The area of the road is 26 × 2 = 52 (square meters), and the area of grassland is 16 × 12-52, = 192-52, = 140 (square meters). A: the area of grassland is 140 square meters

Add "+" or "-" before the numbers 2,3,4,5,6,7,8,9 to make their sum 10
If you allow a number and two digits (do not change the order of the given number, do not add "+" or "-" sign before some numbers, at this time, two consecutive numbers are shown as two digits), can you still get 10? The answer is yes, for example: 2 + 34 + 56 + 7-89

-2-3+4-5+6-7-8+9=10

It is known that the sequence (an) satisfies A1 = 2A, an = 2a-an-1 / a square (n is greater than or equal to 2), where a is a constant which is not zero, let BN = an-a 1 / 2
To prove that the sequence (BN) is an equal number sequence; to find the general term formula of the sequence (an)?

An-a = - (an-1-a), so the N-1 power XA + a of an = (- 1), and the N-1 power XA of BN = (- 1), so BN equal ratio sequence,
This kind of problem can be solved by using the method of undetermined coefficient, which is (an + b) = CX (an-1 + b), and then decomposing to get B, C

Use square brick to lay the floor of a living room. If the side length is 6 decimeters, 80 bricks are needed. If the side length is 8 decimeters, how many bricks are needed

This problem, first work out the floor area of the living room, and then divide the floor area by the area of (a) floor tile with a side length of 8 decimeters. The floor area is equal to the area of (a) floor tile with a side length of 6 decimeters, multiplied by 80
The floor area of this living room is:
0.6 × 0.6 × 80 (Note: 0.6 here is 0.6 m, that is, 6 decimeters. The following 0.8 is the same.)
＝0.36×80
＝28.8﹙㎡﹚
28.8÷﹙0.8×0.8﹚
＝28.8÷0.64
= 45 (pieces)
The comprehensive formula is as follows:
0.6×0.6×80÷﹙0.8×0.8﹚
Answer: need 45 floor tiles
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The following questions can be calculated as they are

4/1÷（3-13/5-13/8）
=4/1÷13/(39-5-8)
=4/1÷13/26
=4/1÷2
=8/1

The x-th power of LIM (x →∞) x =?

LIM (x →∞) 1 / X of x = ∞ 1 / X of ∞ = 0

As shown in the figure, the area of the circle is equal to that of the rectangle. The length of the rectangle is 12 cm. What is the radius of the circle? (take 3)

The radius is two centimeters