1. If the sum of two numbers is 18 and the difference between the two numbers is 4, find the numbers.
Solution: Let the two numbers be x and y, and x>y.
{x+y=18
x-y=4
唔該講下點計。
S1 to S2 ~ Mathematics ~ Extended Questions ~
2007-07-22 4:41 am
回答 (3)
2007-07-22 4:47 am
✔ 最佳答案
先設1,2式x>y.
x+y=18-----1
x-y=4-----2
From 1
x+y =18
x=18-y-----3
Sub 3 into 2
x-y=4
18-y-y =4
18-4=2y
14=2y
y=7
sub y into 3
x = 18-y
x = 18-7
x = 11
2007-07-22 4:52 am
18/2=9
4/2=2
9-2=7
9+2=11
第１題答案是７和１１
{x+y=18..........1
x-y=4
x=4+y..........2
把2代入1
x+y=18
4+y+y=18
2y=18-4
y=7
x-y=4
把y=7代入上式
x-7=4
x=11
答案(11,7)
4/2=2
9-2=7
9+2=11
第１題答案是７和１１
{x+y=18..........1
x-y=4
x=4+y..........2
把2代入1
x+y=18
4+y+y=18
2y=18-4
y=7
x-y=4
把y=7代入上式
x-7=4
x=11
答案(11,7)
2007-07-22 4:50 am
First
x+y=18
x=18-y
Then,apply x=18-y in x-y=4
x-y=4
(18-y)-y=4
18-y-y=4
14=2y
y=7
Then,apply y=7 in x+y=18
x+y=18
x+7=18
x=11
x=7,y=11
希望幫到你
x+y=18
x=18-y
Then,apply x=18-y in x-y=4
x-y=4
(18-y)-y=4
18-y-y=4
14=2y
y=7
Then,apply y=7 in x+y=18
x+y=18
x+7=18
x=11
x=7,y=11
希望幫到你
參考: me
收錄日期: 2021-04-13 13:14:11
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