一條數學題（中一）～２０點～快Ｄ黎啦

2006-11-26 10:12 pm

The value of a is 4 times that of b .If their sum is 45,find the value of a .
我要一條式，最好講埋解釋！！！！！
thx!!!!!!!!

回答 (6)

2006-11-26 10:18 pm

✔ 最佳答案

a=4b
a+b=45
4b+b=45
5b=45
b=9
a=9X4=36

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2006-11-26 10:22 pm

Let the value be A
: A * 4 = b
A + b = 45
A + (A * 4) = 45
A * 5 = 45
A = 45 / 5 = 9
So the value A is 9

參考: 自~

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2006-11-26 10:19 pm

1) a=4b

2) a+b=45
a=45-b

Find b:
45-b=4b
5b=45
b=9

Find a:
a=4b
a=4*9
a=36

參考: Witherhill

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2006-11-26 10:18 pm

A=4b=45
The value of a is 4b=45

參考: me

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2006-11-26 10:16 pm

Let the value be A
Step 1: A * 4 = b
Step 2: A + b = 45
Step 3: A + (A * 4) = 45
Step 4: A * 5 = 45
Step 5: A = 45 / 5 = 9
So the value A is 9

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2006-11-26 10:15 pm

A=4b=45

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