Systems of Linear Equation in 2 Variable

How many can systems of linear equation have?
1. 1 Solution
2. Infinite Solutions
3. No Solution

A) 

If (a1 / a2 != b1 / b2), it involves lines that intersect exactly 1 time.

-- Situation 1

B) 

If (a1 / a2 == b1 / b2 == c1 / c2), it's a same line.

-- Situation 2

C)
If (a1 / a2 == b1 / b2 != c1 / c2), lines are parallel.
-- Situation 3


[Cramer's Rule]

where  is the matrix formed by replacing the ith column of  by the column vector .

 

to solve：http://zerojudge.tw/ShowProblem?problemid=a410
Code:

Ref. http://en.wikipedia.org/wiki/Cramer%27s_rule