兩題中一代數(20分)(急!!!!!!!!!)

1. 7K - ( 9K - 16 ) = 14 - ( -K + 19 )
7K - 9K + 16 = 14 + K - 19
- 2K + 16 = K - 5
3K = 16 + 5
K = 21 / 3
= 7

2. 30 - (2Y - 12 ) = 12 - ( 6Y + 10 )
30 - 2Y + 12 = 12 - 6Y - 10
42 - 2Y = 2 - 6Y
6Y - 2Y = 2 - 42
4Y = -40
Y = -40 / 4
= -10

[ 括號出面有負號的話,拆括號時要小心 D ! ]

若無計錯
1. 7 k - ( 9 k - 1 6 ) = 1 4 - ( - k + 1 9 )
7 k - 9 k + 1 6 = 1 4 + k - 1 9
- 2 k + 1 6 = - 5 + k
1 6 + 5 = 2 k + k
2 1 = 3 k
k = 7
2. 3 0 - ( 2 y - 1 2 ) = 1 2 - ( 6 y + 1 0 )
3 0 - 2 y + 1 2 = 1 2 - 6 y - 1 0
4 2 - 2 y = 2 - 6 y
- 2 y + 6 y =2 - 4 2
4 y = - 4 0
y = - 1 0

7K - (9K - 16) = 14 - ( -k + 19)
7K-9K+16=14+k-19
-2K+16=-5+k
-2K+16+5=-5+k+5
-2K+21=k
K和ｋ一樣？
30 - (2Y - 12) = 12 - (6y + 10)
３０-2Y+12=12-6y-10
42-2Y=2-6y
42+6y=2+2Y
40+6y=2Y
Y和y一樣？

1. 7k-(9k-16)=14-(19-k)



7k - 9k + 16 = 14 - 19 + k



-2k + 16 = -5 + k



-3k = -21



k = 7

2. 30 - (2Y - 12) = 12 - (6y + 10)

30-2y+12=12-6y-10

42-2y=2-6y

2y+6y=42-2

8y=40

y=5

1. 7K - (9K - 16) = 14 - ( -k + 19)
7k -9k +16 = 14 +k -19
16-14+19 = k -7k+9k
21 = 3k
k = 7

2. 30 - (2Y - 12) = 12 - (6y + 10)
30 -2y +12 = 12 -6y -10
-2y +6y = 12 -10 -30 -12
4y = -40
y = -10