請數學高手幫我解答+20點

1)

A+B+C+D = 45

A + 2 = B - 2 = 2C = D/2

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A+2 = B - 2
A = B - 4 ----(1)

2C = D/2
D = 4C ---(2)

B - 2 = 2C
B = 2C + 2 ---(3)

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所以 A + B + C + D = 45
*(1) + (3) + C + (2) = 45
B - 4 + 2C + 2 + C + 4C = 45

7C + B = 47
7C + (3) = 47
7C + 2C + 2 =47
9C =45
C=5 ---(4)

Sub (4) into (3)
B = 2(5) + 2
B = 12 ----(5)

Sub (5) into (1)
A = 12 - 4
A = 8

8 + 12 + 5 + D = 45
25 + D = 45
D = 20

所以 A = 8 , B = 12 , C= 5 , D = 20

2)

先考慮
......61，52，63，94，46......

如果把它們的數反轉
即是61 -> 16 ... 52 -> 25

就會變成
16 25 36 49 64
之後會怎樣?
以上的數都是由一公式 x^2 得出來的
16 = 4^2 , 25 = 5^2 ...
所以下一項數就是 9^2 = 81

把它再反轉就會變成18

答案是 18

Q.1
Let the 4 numbers be a,b,c and d. Therefore, a + b + c + d = 45.............(1)
a+ 2 = b -2 = 2c = d/2 = k. Therefore,
a= k -2
b=k + 2
c= k/2 and
d = 2k . Substitute these into (1), we get
(k-2) + (k+2) + k/2 + 2k = 45
4k + k/2 = 45
9k = 90, therefore, k=10.
Therefore, a = 10-2 = 8, b=10+2 =12, c= 10/2= 5 and d= 2 x 10 = 20.

設該數為 x,
(x-2)+(x+2)+(2x)+(x/2) = 45
.
第二題咁都睇到，佩服佩服~

1. (8+2)=10,(12-2)=10,(5x2)=10,(20/2)=10 8+12+5+20=45

2. (61)=16(4x4), (52)=25(5x5), (63)=36(6x6), (94)=49(7x7), (46)=64(8x8)
所以答案應該係(18)=81(9x9)

1. 8,12,5,20

8+12+5+20=45

8+2=10
12-2=10
5×2=10
20÷2=10
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sorry 2. ng sick