x+y+z=5 x+y=6 y+z=4 In the solution of the equations above, y=? A.1 B.2 C.3 D.4 E.5?
回答 (3)
2016-07-13 6:26 pm
✔ 最佳答案
x + y + z = 5 x + y = 6
y + z = 4
x + 2y + z = 10
y = 5
x = 1
z = -1
Answer choice:
E.5
2016-07-13 6:07 pm
x + y + z = 5 ..... [1]
x + y = 6 ...... [2]
y + z = 4 ...... [3]
[2] + [3] :
x + 2y + z = 10 ...... [4]
[4] - [1] :
y = 5
...... The answer is : E. 5
x + y = 6 ...... [2]
y + z = 4 ...... [3]
[2] + [3] :
x + 2y + z = 10 ...... [4]
[4] - [1] :
y = 5
...... The answer is : E. 5
2016-07-14 12:24 am
subtracting the second equation from the first gives
z=-1
plug that in the last equation and get
y+(-1) = 4, so
y=5.
z=-1
plug that in the last equation and get
y+(-1) = 4, so
y=5.
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