math questions Fast!!!F.2

Lester

2009-10-28 3:29 am

1.Solve the simultaneous linear equations:
11x+5y=10
2x-5y=16
2.Solve the simultaneous linear equations:
7x-9y=27
3x-y=23

3.The total number of pigs and horses in a farm is 150.If 10 more pigs are added to the farm,the number of pigs will be one-fourth of the number of horses.Find the original numbers of pigs and horses in the farm.

回答 (1)

用戶2053

2009-10-28 3:41 am

✔ 最佳答案

1)11x+5y=10 ....... (1)
2x-5y=16.................(2)

(1)+(2) :

11x + 2x = 10 + 16

13x = 26

x = 2

sub it to (1) :

11*2 + 5y = 10

5y = 10 - 22

y = -12/5

2)7x-9y=27 .........(1)
3x-y=23........(2)

(2)*9 - (1) :

27x - 7x = 23*9 - 27

20x = 180

x = 9

sub it to (2):

3*9 - y = 23

y = 4

3)Let the original number of pig be x , hourse be y :

x + y = 150.....(1)

(x+10) = (1/4)y....(2)

(2) - (1) :

10 - y = y/4 - 150

40 - 4y = y - 600

5y = 640

y = 128

sub it to (1):

x + 128 = 150

x = 22

the original numbers of pigs = 22
the original numbers of hourses = 128

👍 0 👎 0