Solve the following simultaneous equations with three unknown.
a+b+c=4 ............... (1)
2a-b+c=0 ................(2)
2a+b-3c=10 ............(3)
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2008-08-17 5:45 pm
回答 (1)
2008-08-17 6:07 pm
✔ 最佳答案
For (1), c = 4 - a - b. ....(4)Put (4) into (2) and (3)
i.e. 2a - b + 4 - a - b = 0
a - 2b + 4 = 0......(5)
2a + b - 3(4 - a - b) = 10
2a + b - 12 + 3a + 3b = 10
5a + 4b - 22 = 0...(6)
Solve for (5) and (6)
{a - 2b + 4 = 0........(5)
{5a + 4b - 22 = 0....(6)
(6) + 2 * (5)
5a + 4b - 22 + 2a - 4b + 8 = 0
7a - 14 = 0
7a = 14
a = 2
Put a = 2 into (5),
2 - 2b + 4 = 0
6 = 2b
b = 3
Put a = 2, b = 3 into (4)
c = 4 - 2 - 3
c = -1
So a = 2, b = 3, c = -1
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