You may use either elimination or substitution for this question.
更新1:
How did you get such x-4 and y-4? I do not understand.Could you explain about it?
F.2 linear equations ( MATHS)
2007-12-14 10:26 pm
Bonnie's age was 7/8that of her husband Clyde's when they got married. Bonnie gave birth to their daughter Dionne one year after their wedding. When Dionne is 19,i.e. 16 years later from now, the sum of the couple's ages will be 100.How old are Bonnie and Clyde now?
You may use either elimination or substitution for this question.
You may use either elimination or substitution for this question.
回答 (2)
2007-12-15 4:45 am
✔ 最佳答案
Let x be the age of Bonnie and y be Clyde'sFor their daughter is 19 years old,so they married at 19 years ago.
(x-19)/(y-19)=7/8
8x-152=7y-133
8x-7y=19.............(1)
For 16 years later,the sum of them will 100 years old.
(x+16)+(y+16)=100
x+y+32=100
x+y=68................(2)
Therefore,(1)+7(2)
8x-7y+7(x+y)=19+7(68)
8x-7y+7x+7y=19+476
15x=495
x=33....................(3)
Sub.(3) into (2)
(33)+y=68
y=35
So,Bonnies is 33 years old and Clyde is 35 years old.
參考: me
2007-12-14 10:35 pm
Let x be the Bonnie's age and y be the Clyde's age
(x﹣4) = 7/8 (y﹣4) ------------- -- (1)
(x + 16) + (y + 16) = 100 ----------- (2)
from (1),
(x-4) = 7/8 (y-4)
8(x-4) = 7(y-4)
8x - 32 = 7y - 28
i.e. 8x = 7y + 4
from (2),
(x + 16) + (y + 16) = 100
x + y + 32 = 100
x = 68﹣y -----------------(3)
Substitute (3) into (1)
8(68 - y) = 7y + 4
544﹣8y = 7y + 4
15y = 540
y = 36
Substitute y = 16 into (3)
x = 68﹣36
x = 32
Therefore, Bonnie and Clyde are 32 and 36 years old now respectively.
(x﹣4) = 7/8 (y﹣4) ------------- -- (1)
(x + 16) + (y + 16) = 100 ----------- (2)
from (1),
(x-4) = 7/8 (y-4)
8(x-4) = 7(y-4)
8x - 32 = 7y - 28
i.e. 8x = 7y + 4
from (2),
(x + 16) + (y + 16) = 100
x + y + 32 = 100
x = 68﹣y -----------------(3)
Substitute (3) into (1)
8(68 - y) = 7y + 4
544﹣8y = 7y + 4
15y = 540
y = 36
Substitute y = 16 into (3)
x = 68﹣36
x = 32
Therefore, Bonnie and Clyde are 32 and 36 years old now respectively.
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